Good day.

Scenario:
Sketch plan from Bureau of Lands is for Lot 300.
This lot is divided into 4 parts: 300-A, 300-B, 300-C, 300-D
The first three parts already have owners but the fourth part is partially owned.
Part of the fourth land is already owned by someone but there's still parts that nobody owned. At least no existing records yet.

Now here is the issue if it can be considered as one. In the records of the Registry of Deeds, there are 7 Tax Declarations for the lot: 300-A, 300-B, 300-C, 300-D, 300-E, 300-F, 300-G.

The lot in which we wanted to be sketched is on 300-F. But based on the sketch plan from Bureau of Lands, there's only four parts being sketch and the fourth being partially owned.

The Registry of Deeds advice us that we could just sketch 300-F on the part of 300-D which nobody owns.
They also suggested that it could be that parts 300-E, 300-F, and 300-G lies on the part of 300-D that nobody owns.

Questions:

Can we just sketch directly 300-F as they suggested with just the walls of the unowned parts of 300-D as the basis?
I'm not an expert on this but my thinking is aren't the parts supposedly arranged accordingly with the basis/start of the other part is the boundary of the previous part? Like the end/boundary of 300-A would be the start of 300-B.

I hope I can have a clearer understanding on this matter with your help.

Thank you.