Automatically migrate to Family Sharing?
Unless I'm misreading your question, doing the following will make the process easier for you:


Launch the App Store app on your iPhone
Tap on your account at the top right corner
Tap on Purchased
Now you should see a listing for all accounts in your family group
Tap on your wife's listing
At the top, below your wife's name, you'll see two buttons All and Not on this iPhone
Make sure that the All button is selected
Now you'll see a listing of all apps* ever purchased under her account
The ones that have the OPEN option at the right are the ones installed on your iPhone
Now make a list of the apps in question so you can delete them from your iPhone and install them under your account


* Accept for any apps she's actively hidden.