I like to see the UVs in the Paint window, even when I’m doing the actual painting in the 3dView.
Is it possible to display 2 different UV maps in the paint window? 2 objects selected displays the “active” (white bordered) Object’s UVs. These 2 uvs share the same texture map.
OR, can I merge the UV maps from two different objects and have them continue to function correctly?
You can make a temporary copy of the objects and join them into a single object.
Not sure if that’s what you were asking with your last question, but yeah, if you merge two objects with same-named UV, they’ll all keep their UV on that map.
(It’s actually pretty useful sometimes to paint on a custom mesh-- it’s actually much nicer to paint on a plane in ortho view than it is to paint in the image editor, lol. Also much nicer to copy UV from a 3D editable flat mesh than it is to edit UV in the UV editor, disregarding stitch and minimize stretch, although not always convenient. Blender’s 2D stuff is very much an afterthought.)