If we explain to Mami that we need to offload so grief, she'd probably understand that we needed to step away for a moment to do it while sparing her the discomfort of Kyubey's presence. She's not as fragile as she was yesterday and probably doesn't still need us with her constantly. Especially when she's got Nadia and Sayaka to keep her company until we get back.
Yep, that's probably what I imagine "don't let him disturb Mami" will end up being. I'm just trying to describe the goal here rather than the methods.
[] Tell Nadia that that's the plan, and thank her for believing and helping you. You
will fix this.
edit:
[x] Tell Nadia that that's the plan. Because these aren't
your grief seeds.
Every magical girl deserves a good life. Thank her for believing and helping you. You
will fix this.
[x] Call Rin and give a heads-up.
[x] Offload a chunk of grief to Kyubey. Not all, but you don't want to be threatening.
-[x] Don't let him disturb Mami.
[x] On the flight over, warn Sayaka that you're... not on such good terms with this group. Quick recap and explanation.
[x] Go to the Sendai Group
-[x] Try to be friendly. Ask how everybody is.
-[x] Cleanse, refresh their Grief Seeds.
-[x] Offer a Clear Seed. Usual conditions, warnings, and instructions.
--[x] Subtly(?) express a hope that, if everybody has one, nobody will have to fight any more.
-[x] Ask about Akiko.