You will probably find it easier all around to manitain one database.
I have my own tree with all its various branches. But over the years, I have extended my uncle’s (by marriage) branch out for a few generations. And my sister’s husband was adopted by his stepfather. My nephews wanted more on their birth grandfather so I have extended those branches. These branches are there and I have them tagged so I remember who they belong to.
When I send a report to a “cousin” I generate the information based upon their filter. A cousin on my mother’s side do not get people from my father’s branch in their report. And which branch are they in on my mother’s side? Her mother’s or her father’s. The filter figures it out and only includes their relevant branches.
One database means only one Place database to maintain, One Source database. And who knows, maybe you will find a crossover between families.
Instead of thinking of your family and your wife’s family as different Trees, they are just the Branches of your children’s tree.