Wait for her.

You all relax and chat while Judy sneaks home. Your bigger ass has you sitting higher than ever.
"So Violet, how'd you like one of these?" You slap your rump.
"I only want to get my butt as big as I need to. That one has gotta be bigger than I will need," she says as she rubs her own butt. "Besides, Judy is all wanting to be your butt buddy. You don't need another. I'll be your boob buddy if you want, though."
"How are you going to carry around big ones like mine without some balance in the back?"
"I'll manage."
"I wonder what's taking Judy so long?"
"Sneaking around, probably. Maybe playing with a dildo cuz she's so horny. I don't know. The big belly might slow her down, too."
You wait some more. You realize there is some pressure in your breasts; you need to be milked again.
"Oh, here's Judy," you say when the door opens again. She is carrying a big bag.
"I squeezed into my one piece," she says as she pulls off the baggy dress. The suit was made for her breast size, so her fat belly simply pulls material from the back. As she turns, you see the ass of the suit is lodged firmly into her crack like a thong.
"I need to be milked again," you tell her.
"Glad I brought this too, then," she says as she throws her sister a similar suit.
"I need to milk you with my ass again," Violet states as she pulls the suit on. Hers was made for her previously small-chested figure. Her tits and clit are soon fighting for the material in the front. She manages to slide the shoulder straps into place by crouching. When she stands, though, her boobs are pulled flat against her torso. This causes them to bulge upwards out of the top and sideways under her arms. Her nipples tent even this stretchy material up top while at the bottom her clit pulls the crotch of the suit out to the end of its full length. You can plainly see her clit and pussy through the stretched leg holes.
"Damn, I got a helluva wedgie," she says as she turns to show you. The entirety of the respectable quantity of butt-covering fabric has disappeared into the crack of her ass. She flexes her butt muscles and she turns her head to look at you to make sure you are watching.
"Yea, that must be putting a lot of pressure on your asshole," you comment. She licks her lips when you look up at her face to answer her. "You want me to lick your butt? Is that why you are licking your lips?" Everyone laughs at this.
"No. I'm trying to be sexy and seductive and all that."