So do we want to invite Laena to be our Lady in Waiting?
I think we ought to just propose a royal progress by the heir (us). This is a normal thing for Targs to do, Viserys didn't, but Jaehearys used to do it all the time. We then invite Laena and Laenor to join us on this royal progress.
Now this has several consequences. First of all, it sends a signal that the Targaryens and Velaryons are united. We may know behind the scenes that this is not true, but to those not paying attention it will seem like we are. Obviously this benefits us and Viserys. It also arguably benefits Corlys and the Velaryons. They don't want to create an image of division in the broader public, he just wants to express his displeasure before the court and put pressure on Viserys to untie their houses.
Now that isn't enough to make Corlys accept this, as he'd probably accept some division if it put pressure on Viserys. However, consider the implication of us inviting his children on the royal progress? The implication is that Laena and Laenor are royals. Corlys is totally going to want to send that message to everyone.
Furthermore, Laena is going to have the biggest dragon, while Laenor is going to be the only male. Corlys is going to think that they will out shine us. I feel pretty confident that we can overcome that. We get our fighting skills back in shape, and show off our abilities. Maybe we hunt some bandits, kill some Dornish raiders or Ironborn raiders. We discuss issues of stewardship and show understanding of the issues that the various lords have concerns about. We treat it as an information gathering tour as well as showing off.
It's also our chance to get to know Laenor. Maybe we can't form a love match with him, but it might allow us to make friends and possibly come to an arrangement. Corlys will be thinking about this as another opportunity to get his blood on the throne. He knows we were willing to recognize a marriage alliance with his family as valuable.
It allows us to make friends with Laena, and possibly she will find a match other than Daemon. Corlys is less likely to accept this, so we don't openly mention it, and we should keep an eye on Laena to keep her out of trouble. Laena is going to want to join us in flying all across the continent.
Now that's what I think we propose. Corlys is going to probably come back with a request that Rhaenys joins us. I think we accept it, letting him feel that he won a concession from us. I think we try to make an alliance with Rhaenys. She understands our position better than anyone else. She also appreciated that we moved to delay Laena's marriage a few more years. I think there is a potential that we can come to an understanding with her. Though she will want us to marry Laenor. Hopefully however, getting to know them both before such a marriage (if it happens) means we can openly discuss things with Rhaenys if Laenor refuses our bed.
I also think that this is a wise move regardless of who our father marries or how the vote pans out.