Not gonna get too indepth but this might put some things into perspective for you.
MIL is 4th (10th from dsc) which is Virgo. Kids are Venus. There was a recent conjunction between Venus and Mercury with Mercury going extremely fast. Conjunctions show a coming together or meeting and it seems as the MIL was very eager to meet them.
You're really in a tizzy over this as the Capricorn Moon and the 8th house placement shows. This is a very blatant indication of stress/anxiety. The next aspect is going toward Mars - your husband - who is located in the 12th house. Is he hiding something? At least he seems genuine in his fondness for all parties (Moon, Venus and Mercury are all in martial signs)
The chart shows a possible solution, and that is Venus' next aspect with its conjunction to the Sun. Sun is exalted in Aries (so is of sterling quality) and Leo is located in the 3rd (intercepted though). Is their a sibling or cousin that you are possibly overlooking who can take care of the children in place of the MIL? That's where Venus seems to be headed next.
Hold up, the next aspect that Venus gets is toward the Moon. So there might a tense meeting between you and the kids, probably an investigation of sorts. After which the next aspect would be toward Mars.