Add a fourth model to the fences (walls)

It happens that sometimes a situation arises, like the one in the picture, and such a gap remains. Sometimes it comes in handy. But I can build that whenever I want.

Would it be possible to add another object like this?

Thanks for your comment on the proposal.

Ohh yeah, was thinking about to add a piece without columns to just fill those gaps, or let the players make the walls wider without the colums.