I think that if you do a solve and say ‘use these results as the reference image for the target’ it will use both the center coordinate and the rotation angle for the target. So I really don’t see why this thread implies something is needed; as long as the plate solving works and as long as you have manually framed the object the way you like it - the whole thing just involves a button push and no manual typing of numbers.
The nice thing about doing things this way is that if you use the exact same solver for the reference image and for the target, and if the centering works properly, then there won’t be any issue with slight differences in coordinates or equinox or anything. It should be a very good match. This is very different from taking an already solved image and using its coordinates as the reference. There may be some discrepancy due to different solvers - I guess 1/2 -1 arc-minute - which may or may not be an issue.
And if you are out in the field and don’t have an internet connection to use astrometry.net - just use PlateSolve2.
Frank