To most easily combine two (or more) templates together, you will want to use the Post Library feature. If you're unfamiliar with how the library works, we recommend watching our video tutorial first.
To best illustrate this, my example will be adding posts from Template A to Template B.
1) Create a library, where you'll be storing posts:
From your dashboard menu, click Post Library, then the New Library button.
Give it the same name as Template A, then save.
2) Add your template posts to your new library:
Select Templates from your dashboard menu, and locate Template A.
To the far right, click the Copy to Library icon and select the new library you just created. This will save all posts in this template to the library you had just created.
2) Add your library posts to the preferred template.
Go back to your Post Library and click on that new library.
Each individual post has a check box in the top left corner. Check the box of any post on this page that you want to add to Template B.
In the boxes provided:
For template, select Exisiting
Choose Template B from the dropdown box
Select the Day and Time
When you’re finished with this page (don't move on to the next page of posts yet), scroll back up to the top of the page and click the Add to Template button.
Those selected posts are now added to Template B. Continue on through any additional pages of library posts to add more posts to that template.