Linking sequences into one timeline

@tara_5071 

When a Sequence is used in another Sequence, it's referred to as a Source Sequence or a nested Sequence.  

"String-out" is the video editing term to describe assembling one nested Sequence after another in the Timeline of a Sequence.

We can insert or overwrite a Source Sequence into the Timeline of another Sequence just like any other clip; however, it's important to be mindful of the button called "Insert or overwrite sequences as nests or individual clips".  For what you have described, you want this to be enabled (blue).  This Adobe learning video shows how to set this at four minutes: Nest a sequence.

Create a new (main) sequence.

Drag each sequence from the Project panel to the main sequence.

https://helpx.adobe.com/premiere-pro/using/creating-changing-sequences.html