you have 2 options... either ignore totally or help them resolve it..
if you choose to ignore it, baka kapag wala ka away ng away yan, makita pa ng kids mo.. bad influence yun..
since yaya B acknowleges the utang, pwedeng salary deduction.. pero unti-unti.. nakakabayad na si yaya b, mananahimik na din si yaya a.. kahit maliit lang.. say, 3500 a month sweldo niya, 500 per month lang madededuct mo.. hanggang dun lang... i think that would be fair naman din