are feeding the other young, there is a chance to reintroduce
these.

But once the parents stop (this is hormonally driven) feeding
then you are not likely to get them back together.

There are birds that are hatched that are equipped less to survive.
Of the 4 I did one was a "runt" and remained so, even with extra food and attention. He did not survive being set free either. I found him dead the next day.

So some are just not strong enough, and maybe that is why you found Maxie. I have also seen young hummingbirds that act tame and stupid at the feeder and I have seen other hummers really pick on those and attack them mercilessly.

So prepare yourself... we cannot reverse a natural weakness.