Info is kinda sketchy. Is 12" an up size or down size from the developed size? Are there a bunch of forms or just one or two? Any reports to worry about?
Applications should be built to accommodate the smallest size you're willing to support so that it fits on anything larger. You could mean as a permanent change or you could be saying you want to do this on the fly so it adapts back and forth to/from 12". I think most re-sizers you will find are meant to enlarge forms, not shrink them, but it's not clear which you're dealing with. You can resize all controls a percentage based on the screen being viewed, but that won't rearrange their left/right/up/down positions. Or you could have duplicate forms if there aren't too many and choose which to open based on the resolution.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.