Cool that you are writing in order to not react back to others' expectations or according to the way they address you. A point of understanding in this case is that yes, some parents will be quite protective toward their kids no matter how 'old' they are, and one has to simply see it as part of the role they decide to play and therefore not creating a reaction according to how they speak to you or address you.
One thing I noticed is that you have indicated how 'they want to feel superior' but this is not necessarily so, that is mostly your interpretation of why they do this and how they feel 'more' than children or younger people, but here, specially when writing Self Forgiveness, it is important to see where it is that you are still asserting things that are not entirely proven to be a fact. In this example, looking at the bold words
I forgive myself that I have accepted and allowed myself to feel less, inferior next to older people who want be more important. When and as I see myself to feel less, inferior next to older people, who wants be more important, I stop and breath. I realize that they see how old I am, and they want be young again, so they feel superior because they so older than me, and they want to show how important they are. I commit myself that when I feel less, I breath and know, that this is their problem, not mine.
The words describing who you think they want to be is a perception or assumption coming from you as well, not sure if they say so directly 'I want to be more important than you' because if they do say so, then sure it makes sense to identify the pattern. But if itis an assumption that you've made based on how others talk to you, then what happens is that even if you are forgiving your reaction, you are still seeing them as 'the problem' because they want to 'be more important than you' when in fact it may not be so.
Therefore I bring this point for your awareness so that you can see next time you are writing self-forgiveness, to ensure that the focus is on yourself, identifying your reaction to another's attitude or words toward you, regardless of what they were 'intending to do' toward you, that's 'their point' not yours to identify or disclose and self-forgive. Another way to look at this point is also clarifying instead how it is you that perceives them as wanting to be more important than you. In saying 'that I perceive, or I believe want to be more important' or 'I react to because I am suspecting they want to be more important than me' then it is you identifying your own belief, perception or assumption of what their intent behind their words toward you really is.
So, to sum up, when self-forgiving it's relevant to ensure we are not re-creating or reinforcing ideas we hold toward others, like say in this case believing that anyone older than you wants to be 'superior' to you, which is most likely not so and even if it was, it's not really a point for you to look at but in general rather bring back to yourself those points of judgment.
Here is where we get to the supportive aspects you can take out from this reaction of yours. Usually we get bothered by others' comments when there is in fact something within those comments/observations or judgments that we haven't dealt with yet. In this case, I would then suggest you to open up, what kind of judgments, ideas, perceptions do you have about yourself being of a certain age, having no 'family' or relationship or kids or job or all of those things that you have also accepted are to be 'expected' at a certain 'age' in your society. This way, instead of only working with 'not reacting' to your older family members, how about taking those judgments 'back to self' which means investigating where and how you may be judging you for not having all of those things that you might believe you are 'supposed to have' at a certain age. This is where it takes a self-honest look within it, because if you were completely fine and ok with how you are living your life and your decisions within it, then no matter what anyone would think or say, you'd be stable, which means:you know who you are, why you do or don't do things and that's about it, that's you being entirely aware and responsible for your creation. So, here it is then a cool opportunity to rather investigate if there is a form of discomfort or judgment existing within you toward all of those 'expected things' you were supposed to be doing or having at this age you are now, and so be able to forgive your own ideas, judgments or expectations about it.
What this step will create within you is a clarity of 'who you are' in relation to those things others talk to you about like say having a certain kind of job or family or relationship or whatever it is that you may think you 'don't have' compared to others. This way it won't be about 'who's right or wrong' about things, but rather ensuring you are clear, certain and stable within the decisions and choices you've taken on in your life. Through writing out this and being able to stop the reactions toward others or your own judgments, you will then also be able to identify if there is something you'd like to genuinely change, create or expand in your life. Then it will be your absolute decision within having investigated these ideas about 'who you are' and rather looking at what is it that you genuinely want to be doing and making of your life right now.
And remember that no matter if another 'insults' one, the insults are stemming and being created in another's mind, it's their point to consider and eventually become aware of. But whenever we react to it, we become part of the judgment game and that's where we have to look at what is being triggered within us within a certain insult and when investigating such insult and finding what 'bothers' you about it, you may also then find something else to align within you or work on or change, so that such insult instead becomes a point of awareness about something within you that you can change about yourself, because in one way or another was bothering you. This can be 'taking things personally' in itself, and so when listening to such words next time, investigate further as to what is it that is being triggered within you, making you react this way. It might then become a very supportive way to face the same people in your day to day and continue working with these points in detail within you, until no matter how many times you might hear that in a day, you remain stable and not reacting, because you would have been working with aligning, correcting, stopping reactions to those same words or judgments.
This way one no longer sees others as a nuisance, but rather as points to face and clear within oneself only.
Enjoy and do ask if something of what I shared here is not so clear