I've been married to my wife for 5 years. She has two kids from her previous marriage Jason- 22M and Carla- 19F. When we married, my wife still had 50/50 custody of her kids and she wanted to move into my house.
I converted the attic into a bedroom so both of her kids and us could have our own rooms. Their father is present in their life so I was pretty much designated the guy that married their mom and I'm fine with that.
I sorely underestimated how much having two teenagers in the house would increase bills. When I was single I could do my mortgage and bills fine on my own. Post-marriage everything but the mortgage has gone up, not including spending money for the kids and their extracurriculars.
My wife got child support from her ex and some extra help with their expenses, which helped a bit while she had it, but I still had to dip into my savings a lot. It was really important to my wife to be a stay-at-home mom until they graduated. It was tight but we made it work.