FET - transfer one or two embyos?

Just wanting some outside perspective/advice!

I'm planning on doing an FET in January. I can only afford to do 1 transfer so whether it works or not I probably won't do another one. I have 3 children so will be my last!

I have two embryos (both low level mosaic) and am trying to decide if I should transfer one or two since it'll be my only transfer. So in my mind transferring two would give them both some what of a chance rather than picking between the two and hoping I made the right choice...

I know the risk of twins but I feel like I would be okay if that ended up happening. I'm more worried about one of the embryos not taking and making the other not implant when it would have or something 😂 Is that a thing? I feel like I've heard that somewhere.

Is that something to worry about? What would you do if it was you? I'm kind of a hot mess right now so thank you for reading 🙃