Company B is new, has no baseline and I'd work myself probably near to death for the next three to five years to get it established in a very competitive market, probably missing my kids' formative years (they are 3 and 4).
First, can you transfer to another position or department in Company A where you'll receive a pay bump? I was in the non-profit sector for most of my career, and it was common for folks to jump into management positions for a pay bump. (This might not work in your case, since you mention you're already in a management position.) But, how about a different department altogether?
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