Repository -> Repository Settings -> Remotes -> Edit Config File..
Put all your remotes in a single origin remote section, see below for example :
[remote "origin"]
url = https://myaccout@bitbucket.org/mynickname/myrepo
url = myuser@192.168.1.61:/srv/git/myrepo.git
fetch = +refs/heads/*:refs/remotes/origin/*
pushurl = https://myaccout@bitbucket.org/mynickname/myrepo
pushurl = myuser@192.168.1.61:/srv/git/myrepo.git
References
- https://community.atlassian.com/t5/Sourcetree-questions/Push-to-multiple-Remotes-with-Sourcetree/qaq-p/109260