Whenever I need to create multiple merge requests for Git, I use shell scripts in CLI.

#!/bin/bash
merge_request() {
        cd $1
		git fetch "git@gitlab.its-newid.net:$1/$2.git" master
git checkout -b "$1/$2-master" FETCH_HEAD
git fetch origin
git checkout "master"
git merge --no-ff "$1/$2-master"
git push origin "master"

        cd ..
}

merge_request dev _env
merge_request dev _lib
merge_request dev _bot
merge_request dev api.its-newid.net
merge_request dev ads.its-newid.net
merge_request dev partner.its-newid.net
merge_request dev live.its-newid.net

In above case, you will need to register SSH certificate at GitLab server.