I have been growing tomato plants (Moneymaker variety) in my garden in the netherlands for a couple of months. They seem to have grown well.
When they first came out of the earth (seedlings), multiple stems emerged (up to 5) and I have let them grow together. Now I am worried they might suffocate. I've attached a picture. What do I do from here?

Another option would to just let them lay down gently and sprawl out right on the mulch if they have the room.
They look low to the ground enough to accept that it seems...

I didn't research tomatoes before putting the stake through! and honestly, I think I planted them too close together (I also didn't think they would survive... they are about 1ft+ apart.)
I've actually built a greenhouse structure around the tomatoes, how about supporting them with strings (attach the main stems to a string and to the structure above)?
What would happen if I drove a stake through the roots?

The Teepee system sounds feasible. While the last option sounds tempting, I have got ground space restrictions, since I am growing in a raised bed.

Whether you remove 1 or 2 of the stems by cutting above the fused point is up to you but as long as you can support the plant well as it grows I'd just leave it as is.

Dave