Issues with iPhone Http Streaming

Question

We are seeing is when "tying" to video files together.

Example we have Ad video that is segmented and content file which is also segmented. We create a new file which has both Ad and content segment information together. However we are seeing an issue where either the Ad content is truncated or the content starts having A/V sync issues. Both ad and content are segmented the same way , 5 sec segmentation. however since Ads are variable length the result file may have left over segment something like:

#EXTM3U
#EXT-X-TARGETDURATION:5
#EXT-X-MEDIA-SEQUENCE:0
#EXTINF:5, 
fileSequence6.ts
#EXTINF:5, 
fileSequence7.ts
#EXTINF:4, 
fileSequence8.ts
#EXTINF:5, 
fileSequence0.ts
#EXTINF:5, 
fileSequence1.ts
#EXTINF:5, 
fileSequence2.ts
#EXTINF:3, 
fileSequence3.ts

Is this the proper way to play 2 files one after the other without rebuffering? should generate-variant-plist be used to a play list of 2 files?