Creating a quotation from a custom pricing Doctype

I created a new doctype that we use to calculate the pricing sheet for the quotation, I also added a custom button that creates a quotation after submitting the pricing sheet doc, I am trying to take the values from the table in the pricing sheet and ‘export’ them to the created quotation using ‘get_mapped_doc’ function, however when the quotation is created the values from the price sheet are initially loaded correctly then they get overridden by the price_list_rate.

Does anyone know how to solve this issue ? Thanks in advance.

Refer this