How to make new cat happier in her safe room?

Pumpkinseeds

All going well we should be bringing Pepper, that name suits her better than Summer, home to live with us next week. I'm going to have to confine her to a room away from our 3 male neutered cats. I've never had to confine a cat like that and I want to take as much stress as possible out of it for her.

We'll put a Feliway difuser in the room, a litter tray and a snug igloo bed. Jazzy won't be happy, it's his safe space and he sleeps there most of the time but it's the only place we can put her. I'm just looking for some practical advice from people who've introduced cats this way. The timing could've been better but we don't want to leave her where she is much longer.

Nody

You've covered most of it I'd say; only thing I'd add would be a few toys, a few cardboard boxes (some flipped) to give additional hiding space and a radio to play on low volume (human voices).