Interesting that BLQ decided on a crackpot frame-job for Willow with Lucy, rather than...
...asking her about any nice listings for a little family of three. Honestly, if that were my dumpster fire of a marriage and I were making last-ditch efforts to save it, relocation would be paramount. Willow may use her kids as little pawns to weasel her way around Chase while they're on the Q estate, but if the Chases are no longer living on the Q estate...Well, it's not a perfect solution, but will make it glaringly obvious (even to someone as oblivious as Chase) that Willow is on the prowl if she were to begin showing up on his non-Q doorstep.
The nanny, the big loving family...it's all great. And at this point, zero percent necessary for Phoebe's well-being. She's infant enough to only need and benefit from her parents right now. A year or so down the line, sure...being around more people and all that will be good for her, but now is the time for their family to be insular and really bond.