DH and I have two kids, 6 & 8. DH works away 3/3 weeks home/away. MIL lives 2 hours away and is the main childcare for our niece. MIL wants to visit us, but this needs to coincide with SIL’s annual leave, which she has arranged, without asking first, for when DH is away. I don’t want MIL visiting when DH is away, as I’ve already arranged holiday clubs for the kids whilst I’m working. I’m getting frustrated that SIL’s childcare requirements seem to dictate when MIL is able to visit us. It’s already a bone of contention between DH and his sister, as we think MIL does too much (she’s late 70’s, niece is 5). AIBU expecting SIL to arrange alternative childcare so MIL can visit her other two grandchildren. For context, she’s seen them for 2 days since October 21. Us visiting her is not an option due to work commitments.