Very glad that you guys are talking about this and that you used the time you had to get to the details of some of this stuff.
While I don't even begin to understand your desired dynamic, I think that you are developing a very clear picture of what it is that you need and want in life, and are working out the path you folks need to take to get there. That is truly fantastic. Many couples don't get this far....
I also like that you are seeing that for Colada to take much of a role with your kids, you are going to need to meet her, and get along with her - putting aside your d/s kink desires, the kids need to have a solid framework to grow up in and not a drama-filled house with mixed-messages being put out there because one female says one thing and the other says the opposite because they haven't been able to sit down and discuss what needs to be done.
One more thing to think about - if all three of you are contributing to the finances of the house, that gives each of you a say in the big house decisions. If you and she don't have some sort of working relationship by this time, then Piper is going to have to play the diplomat and go-between on every little thing. I have experienced this personally in a very small way and it is truly exhausting and not very effective. I can't picture a functioning household where you and she don't have some sort of working relationship (and I don't mean romantic, just functional).
"Listen, or your tongue will make you deaf." - Native American Proverb