Generating a table in a PDF-Invoice

[BOTFORCE]

Dear friends,

I need some advice how to create a select-statement to generate a table in a pdf over 3 tables which are related as following:

In my first Column I need the name of the client from the Customer table and I start with:

<<Start:SELECT(INVOICES[Invoicenumber],true)>> <<[CustomerID].[First name]>><< [CustomerID].[Last name]>>

In my second column I need the grave inscription  from the Graves table. As my starting point is the Invoices table I do not know exactly how to retrieve this information.

Thanks for your help,

Robert