Got company. $100 missing. Here's what I've done.

[centaurmyth]

Trust that your brother (in-law?)'s care for his son is strong er than whatever has gotten him wound up and speak with him frankly about it. Even if he is angered with the difficulty of what to do, or angered by his own ownership in the situation, and projects it onto you. Behind it all, it's for your nephew's benefit. You said it, "I probably should."