Re: TOS S4 - If You Could Add to a Previous Storyline
In my personal continuity, the Five Year Mission consists of the three seasons of TOs and the two seasons of TAS.
Then TMP happens, and is followed by the Unseen Phase II scripts written in the late 70's - these happen between TMP and TWOK. there seems to be plenty of room for them there.
USS Galileo Galilei, NCC-8888
Starbase 31, Daran V
Prima Inter Pares