Dependency from a cell on another sheet

Hello,

I run my manufacturing jobs on Smartsheet.

I have one sheet with multiple projects on it, Parent row per project and tasks indented

I have a few milestone dates in each project for equipment arriving (this date is linked from a shipment tracker) which other task tasks within the project are dependent on before the project can start, but don't necessarily start when the day the equipment arrives. but a problem I have is the overall project start date goes by the first date (equipment arrival date) which isn't actually the date the project starts, so the overall duration of the project is incorrect, meaning i cant measure how long the project actually took

- Is there any way i can make a task dependent on milestone on separate sheet?

- Or is there a way that i can make the project start date (on the project parent row) start from the date the work actually starts, not from a milestone?

I have attached a screenshot with an example

At the moment when i look at look at my projects in Gantt or calendar view, the length of the project is far longer is inaccurate and looks really messy.