1：关联第一个仓库

git remote add first 远程仓库名

first为拉取下来之后本地的名称
2：从该仓库创建并切换一个开发的分支

git checkout -b feature/first

3: 关联第二个仓库

git remote add second 远程仓库名

4: 从该仓库创建并切换一个开发的分支

git branch feature/second second/feature/second

这里假设远程仓库的开发分支为feature/second
5: 第一个仓库同步第二个仓库

git merge second/feature/second

6: 将同步的代码推送至远程仓库

git push

7: 如果后续第二个仓库有更新
1）切换至feature/second

git checkout feature/second

2. 拉取最新代码

git fetch second feature/second
git merge second feature/second

3）同步至仓库一

git checkout feature/first 
git merge feature/second

4. 推送至远程仓库一

git push