Click on the timeline to place the cursor where you want the theme Designer template to start. Found that going to Plugins/Theme Designer it works like it should. The Theme Designer templates will be where one wants them on the timeline.
Go to Plugins/Slideshow Creator and select a Theme Designer template and get the same issue of having the whole timeline replaced. This is confusing some users that accessing Theme Designer in Slideshow Creator has this issue. I believe this issue is a bug that needs to be reported to Cyberlink Support.
Does any one else use Theme Designer and find this problem? I will write a support ticket if another user can confirm this issue.