Server updated to 1.16.  Player entered server first, and a dozen dogs tied to a fence via lead teleported to him, and the leads drop at his feet.

We reattached the leads to the fence and unloaded the chunk (through nether portal).

A different player returned first to load the chunk and dogs were sitting and tied up.  Owning player then came through and the dogs stood up, still staying tied.

Both players went back to the nether, unloading the overworld chunk.  The owning player went through first (to be the 'chunk loader').  The dogs immediately teleported to him (while he was still in the portal, shoving them through) and the leads dropped at his feet as well.

Oddly, 5 of the dogs stayed tied up on the second test, but 10+ teleported.