Task and Subtask App for single user

Thanks @Ofer_Chama for quick response. I could able to manage to link Clients to a particular task. However, I am thinking to put some “Unique ID” to my Main Tasks which can be linked to subtasks, not sure how to do it because I already have list more than 100 tasks and more than 200 subtasks.

I really liked your suggestion of using IfThenElse. I will surely do this.

Even if I create all the sheets like you mentioned, how would I add task and subtasks using single Form option?

I will create the first cut App and will show you if that can help you to explain me better.

Thanks a lot.