Note to self (for all the good it will do)

Be sure of your science before you start writing.

So I have pretty much resolved the aforementioned monster plot hole, but naturally the solution created more issues. Or rather my choice of solutions did.

I could have the second mission leave 10 years after the first and arrive ten years after them as well. I confirmed the relativity by drawing a little chart. That would conveniently make the sister exactly the age she should be for the story.

The problem with that scenario is that I also need Earth to know what happened on the first mission to prepare for the second. This means leaving after the events of the first book, which in turn means they have to travel faster than light. I really hate to use this worn out trope, but I don't see a way around it. The first mission already has wormhole communications, so I guess it is a small step for them to figure out wormhole travel in 30 years.

The quandary this solution leaves me in is that K, who was ten years younger than her sister when the first mission left, would be ten years older than her when she arrives.

I could write around that, but I don't want to. I have written her as brilliant but a bit naive, and I like that. She simply can't be a 46 year old seasoned veteran.

So, current idea: have K be the niece instead of the sister. Then the ages work out.

See why I say to get the science right the first time?