I would suggest to NEVER switch eggs. I had an olive egger hen, that had always wanted chicks from day 1. She was always sitting on eggs and acting broody. Once, I let her sit on 4 fertile eggs. She was a dedicated mother, and she never (not once!) got out of that coop. Around day 15 she died. She wasn't eating, and she wasn't getting enough exercise. My other hens tried to sit on the eggs like she did, but they got bored fast. One of them actually stepped on an egg! It was gross! I feel you on that one. So, I put the eggs in an incubator. They were wiggling, moving, and responding to me when I talked. Finally, on day 20, one of them piped. I was so excited! The chick took a few more shots at the egg, and died. My house smelled horrible. But I left the eggs in there for 5 more days, nothing. I lost a good hen, for nothing. If your hen isn't leaving the eggs, you should shoo her out for a few mins every day. If she still won't leave, I would suggest taking the eggs, don't risk it. Eggs can always be reproduced, good hens cannot. Losing a couple unfinished chicks that you don't even know, and you've never met, is better than losing a pet bird that you love. I would leave the eggs, IF she looks healthy. If not, put them in an incubator. My opinion, a hen is the very best incubator there is. If there's one thing I learned (other than what I already told you) eggs do NOT like being moved from a first class fluffy butt, to a third class plastic incubator! As my mother says, "let nature run it's course". If you're worried about your hen, take the eggs, but I've learned that switches rarely work. Others may have different experiences though.
