You could always buy cherry scent and squirt it on or cherry potpourri and put it in a ziplock baggy for a couple weeks with it.Or try any different fruit scent on the dolls too.That can be for Cherry Merry Muffin,knock-offs etc.

I'd be concerned about squirting any kind of essential oils onto the plastic. Anything else wouldn't really last though. I have thought about scented candle wax though... if it was melted onto it on the inside, that might give the dolls some smell, and the wax would hold the essential oils, so it shouldn't damage the doll like putting it directly on the doll could.

what about stuffed animals? i was thinking of rescenting my yumyums to resell them. i was going to use a drop of scented oils on the top of the head

That'd probably work. I don't think they should be for little kids anyway, so it should be OK.