Years ago, at my chain saw repair shop, if I brought in a broken chain they would put a couple of other links in from another used or broken chain. The didn't like to put "new" links in as the chain was used and then the part of the chain that slides on the bar would be higher at the new part and therefore the chain would have a sort of hump in it as it traveled around the bar.
They didn't do that for very long and then they told us their insurance company wouldn't let them repair broken chains that way any more.
I don't know if that was just a way for them to sell us more chains or not. But after that I never got a broken chain repaired again.
But, since then, I can't remember ever breaking another chain. Now I mostly use them up.

For this reason, adding a new link to a used chain, could be the reason they won't repair any or sell you any repair links.

You could try and see if there is anyone who could weld or solder some new teeth onto your used chain. I don't know where you could get some new teeth either.

You might have to get a new chain as well as a metal detector for your timbers.

This barbed wire didn't show on any of the four faces of this timber?

Jim Rogers