Reusing registration from existing multiple nights – #3 by Epoxid – Siril

Thanks! I know that guide, and I always thought it meant “take the bkg_pp_* from each session, throw them together and register all”.

I was wondering… I have two sessions with individually registered r_bkg_pp_* files. Can I throw these two together and relate their registration to each other?

Or can I have one session of registered image r_bkg_pp_* and one session of unregistered bkg_pp_*, then throw the unregistered images into the registered session and register only those new, unregistered images to the existing ones?