I can tell you that personally, generally speaking, I am happy to buy out angels from earlier rounds.
I’ve done it twice this month, in fact.
Because almost always, I want to buy more shares than I am allocated. Almost every time.
But don’t ask me (or someone like me), usually. You can, but usually, it’s better to just ask the CEO. It’s better for her, and the company, at least at the margin to get an angel off the cap table that wants to exit anyway. If it’s in her and the company’s interest, she’ll just email existing and new investor and see if she has a buyer.
I buy these shares all the time.