When he learns his mom has only months to live, a self-absorbed, corporate executive must find his estranged siblings to re-create childhood photos so they make a final gift to their mother before she dies.

This sounds like it has the makings for a nice drama, but I could also see it making a nice comedy - depends on how you choose to swing it.

I think best to define the inciting incident in more concrete terms - After his mother is given a month to live...

It is a relatively low stakes premise. If they fail the mother dies with no visual reference of their childhood, if they succeed she sees some photos - she is no better or worst off either way.

What if, as a result of her condition,? she lost all her memory of their childhood? Now, instead of showing her something she's already seen, the siblings have a month to give her back her memory's of their times together.