How to add a "Employees" multiselect field on projects?

Hello there, i'm trying to add a custom field on project view screen very similar of ticket system:

I go to record browser -> recordset: projects -> managefields tab

See the row in red (now is deactivated cause if is active project modul crash and send me this error https://www.lyrbasystem.net/extranet/data/Base_Error/2dcbd5b5973cf9dc97a077a1c26009fa.txt)

I think that the problem could be conguration of Value display function and Field generator function:

Is this posible?

New version of Projects module includes a patch which will add multiselect fields for Customers and Assigned Employees:

New Projects fields

Please note that "Freelance" is a custom field.

It will be available soon in EPESI Store in updates section.

That's great, i thought that I was close but seems that i'm totally lost.

Thankyou Jasiek, great software.