This (untested) SHOULD work fine.
Code:
function create_my_bmap (BMAP* this)
{
	BMAP* fb = bmap_createblack(256,256,24);
	BMAP* this;   
	wait(1);
	// do something with fb
	...
	//
	wait(1);
	this = fb;   
	BMAP* that = fb;   
	//is now done!  both "this" and "that" and "fb" are ALL pointing at SAME bmap.
}
But I would try to avoid this type of programming, its going to be very easy to end up with "invalid pointer" errors.

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