Hi Eva,
I wanted to get back to you with regards to how you would link the bills under vendors with a field services work order. In order to do this, I'd like to take a moment to explain what work orders are. Although they appear as "work orders" under the Field Services tab, these records are actually listed in the general "activities" table, that lists all activities across Method, and are given the property type "Work Order", but under the hood they are still activities. This is one of the key advantages of Method as it allows you to see all your activities in one single place.
What you have to do is modify the Bill table under Customize -> Tables/Fields -> Bill and add a work order drop-down field that retrieves the "comments" value from the Activity table, as "comments" is the actual name of the "Work Order name" field. Then you simply specify the appropriate columns that your drop down field pulls from the "Activity" table, and voila!
If you would like more help with this, please contact our customization expert, Michael Melo, and he will be able to walk you through creating this relationship.
Regards,
Denis