My bridesmaids teenage step kids want a plus one each?

I have no idea how to handle this one.

My bridesmaid (28F) has 6 kids. They are all invited to the wedding and her husband will also be attending.

We are NOT having the bridal party sit with us at the head table because we didn't want them to have to sit separate from their significant others and make them feel awkward.

Instead, we are having assigned seating at the tablew closest to us for our immediate family, aunts/uncles/and bridal party and their family. All of our cousins are old enough that they have their own families and will sit free range with the rest of the guests, but we were trying to keep the older and immediate family members up close. The counts happened to work out perfectly

So my bridesmaid has just informed me that her daughters (I don't know them well, they are her step kids and have a different mother) want to bring their boyfriends. I don't have any space at the front tables now without removing an aunt or uncle.

I was taken aback that her teenagers expected a plus one, but I wasn't going to refuse them.

Would it be terrible if I didn't out the boyfriends at the reserved table? I don't want to hurt anyone's feelings.

The layout isn't so simple as adding an extra table. As they are 24 feet long tables and we have already purchased all of the tablecloths and decor. I will have enough seating and tables overall for every guest plus 30 extra seats. I just don't have room at the family table.

What do I do?