HELP Please - How to create transitions between clips + synch the clips

Hello guys

I recorded this video explaining my problem: Video Template Creation Help | Loom

1 - is there a way to add transitions between the clips so it’s not abrupt
2 - How do I synch the clips so that the next clip starts when the previous is finished

Objective:

Create a template that is divided into 3 sections : Intro / Body / Outro

I will then rotate some intros (same for outro) and just populate the body with the video of the day.

Does it hep if I provide the JSON? or anything else that might help?

If you have a similar template would you mind poiting me in the right direction?

Thanks

Can’t put the JSON here because there are restictions on new users who can’t put more than 2 links

Here is the JSON: JSON shotstack template.json - Google Drive