You don’t need separate accounts but you need separate applications. You can also make all 3 applications from one account. Me and my husband always use same account.
You need to apply separately for all the dependents because if you do on the same application then it will ask you to fill the forms for open work permit and study permit instead of TRV. So you should do separately. This is how it works
I think its “Travel document” that is our passport not tracking document. Every case varies may be they required some to do so… but for me and my brother they didn’t ask for this.