Hello @Pannir ,
I would be looking for "Dropdown" common field.
With just a piece of JavaScript you can handle the data inside.
Use this - Official Plumsail Documentation - Common field - set data source
fd.field('Field1').widget.dataSource.data(['New option 1', 'New option 2', 'New option 3']);
Do a logic in a function when the number 2 and 3 should and should not appear.
When the dropdown is changed:
Dropdown field is changed - Official Plumsail Documentation
Set the choice field value based on the selection:
Choice field - set value - Official Plumsail Documentation
If you need further assistance, let me know 
(Apply for the newform)
When opening EditForm - you must think about loading the value back to the dropdown. Also in the DispForm, you should only show the Choice field with the value.
Regards
Stepan