I recently had to tie two ropes together because the tree I was in was just a bit too large, I used the zeppelin bend and then tied off the ends with double fisherman's to back em up, worked great! Of course I didn't sinch the double fisherman's super tight so they could be Un done easily.
https://www.ebay.com/p/Jonsered-CS-2139T-Chainsaw/97469694
I don't know if I'm allowed to link like this, but I found this bad boy fairly quick, Goodluck!