I spent the first three/four years of retirement (from aged 50) providing care for two elderly and increasingly infirm family members. I didn't need to provide any financial support: they were modestly but sufficiently covered for all their financial needs. I did provide a lot of personal support which took time and energy. I have no regrets (except possibly the sale of my sports car after 23 years of ownership so that it could be replaced with something more suited to my elderlies' needs - but I don't expect that to get any sympathy on these forums, and quite right too).
I think the advice you often hear about putting your own seat belt on first is right, but I would take it a step further: providing long-term personal support for family members is hard work and time consuming. However much you love them, and however much you are choosing to do what you think is the right thing, it is still hard work and time consuming. If you added to that resentment about what you are losing out on, or financial detriment to your own position once your caring duties are over, then the caring would become even harder and I can see it could easily create toxic feelings in you and in the relationship you have with your family members.
So my advice would be: do not, whatever you do, overcommit yourself. Start very, very small, so small that it is immaterial to the life you want to lead for the rest of your life. Be extremely aware of "mission creep": your family's needs will quite likely increase over time, or they will become more reliant on you saying "yes" over time, and this could go on until there is nothing of "you" left. And once you start on providing a certain level of support it is extremely unlikely that you can go back on it in the future. So I would tell you to set boundaries, and to set obstacles for yourself before you allow those boundaries to be crossed (eg set wait times before saying yes, going through certain paper exercises before saying yes, consulting other family/friends before saying yes). There is no shame in getting to the point where you say "I can't do this any more, my family members need more help than I can provide".
I had two very firm boundaries: I was not going to move from my (ideal) FIRE location or my ideal FIRE house which was not particularly suitable for them. My family members moved to be close to me, which was not easy as they were leaving the home town of a lifetime. It was made easier by the fact that other relatives and most friends had already died (they were both in their 90s) that they were moving nearer to some long-term friends/family who they could see more easily, and that they were moving to a comfortable and manageable home, seeing me daily and having new things to do and people to meet. So not ideal for any of us, but a good enough compromise that I think there were no regrets on either side.