Copy multiple chapters to another study (or split a big study)?

Is there a good way to copy multiple chapters to a different study?
I know I can download a chapter PGN and then import a new chapter from the PGN, but it is too slow if I'm trying to copy a lot of chapters. My study have grown too big (for the 64 chapter per study limit) and I need to split it into two and move about half the studies to the new one.

A very interesting question that also concerns me.
I'm curious if anyone can help here.

What I do for big cases is clone the study and then delete the chapters I don't want.
The drawback is the message "cloned from ..." but when I don't mind it it's the fastest way.

@pepellou Thanks, your hint helped me!