Hello Gigha,
for each "Document" object in 1C, a predefined "Filling" procedure is available (pic. 1 and 2).
This procedure is called when one object is created based on another, for example when you make a "Sales Order" from "Quotation".
The "FillingData" parameter is passed to this procedure, which contains the data of the "parent" object.
Thus, using the "Filling" procedure in the "Sales Order" document, you can process the data of the "Quotation" document and fill "Sales Order" with the necessary values.
Look at image 3 - there is an example of this procedure from the working program for the document "SalesOrder".