This was the first offer at OLCI for my 3 year-old and me a few weeks ago...
A few days later, I ended up being given this...
Don't forget the VY OLCI opens 7 days before departure. If you don't like your assigned seats, you can cancel check-in and come back later. (once you confirm your seats you cannot change later, at least without paying IIRC...)
If you have any concerns, just pay for seats. Spanish law does NOT require parents and children to be seated together.