That was a nice, brief response to her email pushing you for an answer. Well done.
Aren't you going to send her that other email about S9 schedule? That is where you and W need to focus on and get that worked out. I do think it's important to express your desire to spend some time with S9 on Father's Day. Put it out there and then sit back.
Hi woka. We've sorted out S9's schedule for next week you'll be pleased to hear. I'm going to let Father's Day slide. I had an early one with himast week and he's super excited about the trip so I don't want to stop him from going. Besides, he keeps saying how he wishes I was going.'perhaps he'll say that to his mother.
Me:43 Her:42 M:14 S:9 EA started 2014/03 (or there abouts) PA started 2014/05/30 BD:2014/11/05 I left 2015/10/01 I returned 2015/05/02 She left 2015/06/10 OM still on the go.