I am an experienced FileMaker developer and have been developing applications using FileMaker for the last 12 years ranging from complex CRM systems to Website Content Management as well as solutions utilising FileMaker Go.
I have developed several CRM/ERP systems which included the development of modules for Invoicing, Quotes,Sales Orders,Stock Control, Suppliers Invoicing, Stock, Purchasing and Work Orders.
There was also the requirement to show visually in a graphical Scheduling tool what was works were being carried out and by which resource ie. engineers, and it may be possible to modify this program to work with your requirment.
For one manufactoring system I also implemented functionality in the Stock module to build Assemblies from the existing stock items as well as managing their actual Stock levels and flagging when stock should be reorderd.
In the course of these developments I have gained a lot of experience with the use of third party plugins to extend the power of the Webviewer, FMBooks which was used to integrate FileMaker with QuickBooks and a Sage utility used to export client, Suppliers and financial data directly into Sage.
The majority of the system I have developed have all, if not some of the elements you require, therefore I believe I would be well suited to build your project
If you would like to see some examples of my work then I would be more than happy to arrange an online meeting with you to demonstrate them.