So how do you get a timeline that minimizes the civil wars over succession?
The civil wars were caused by the premature deaths of the emperors coupled with the lack of acceptable heirs , so it would be easy to avoid the wars by avoiding those deaths.
Option1:
- Manuel , Michael's youngest son , is not accidentally killed by his older brother's men
- because he hasn't lost a son , Michael lives longer and dies in 1343 ( he would have been 67 years old )
- Andronicos III dies prematurely , as in OTL , in 1341
- Manuel becomes emperor in 1343
Option2:
- Michael lives longer and becomes emperor after his father's death ( 1332 in OTL ) and reigns until 1340
- Andronicus III succeds him and due to the butterfly effect , dies in 1361 , ( he would have been 64 years old )
- he is succeded by his son John , who should be about 30 years old
Option3:
- Manuel is killed as in OTL
- his mother dies due to grief instead of his father
- Michael marries someone else and has another son ( let's call him Constantine ) , born in 1322
- Michael reigns between 1332 and 1345 , dies at 70
- Andronicus dies prematurely in 1341
- Constantine , now in his 20's becomes emperor
A POD in 1320 or 1319 is rather late if you want the Byzantine Empire to become one of the strongest states in Europe , but if you avoid the civil wars , you should come up with a relatively stable empire which is a regional power.