My SIL was like this (& like thatagain's SIL). She was my SIL for about 40 years & pulled stunts like this all the time.
Specified expensive gifts, asked for money, gave us cr*p cheap gifts & even things we'd given her.
Told us she'd got Xmas presents ready to send to us, so I sent ours to her family, then she rang to say thanks for the gifts which have just arrived, sadly yours are not postable so they'll have to wait until we see you (no plans & we didn't see them for 18 months).
Would also send semi-decent presents but with no protective wrapping so they were damaged on arrival: very passive-aggressive.
After our wedding (which she made trouble about) demanded that we send her the entire, very heavy official wedding photo album - er, no.
As you say, it's easier when your DH is on side with it all. Mine, bless him, wanted a happy family - don't we all - & kept expecting/hoping that she'd be normal. I was 95% certain she wouldn't be but retained that 5% of hope until she died.
This smells of CFery. Decide what you want to do, do it & ignore the fall-out.