Subpanel in Employees module

Dear Experts,

I want to add Document and Contracts sub panel in Employees module.I am not able to add one to many relationship between Employee and Contracts module as Employee module is not showing in modules dropdown.

I want to display all the assigned documents and contracts in subpanel of the particular employee.
I have also tried by adding custom relationship with Employees module through code and also followed this link

but sugarcrm log displays the error invalid subpanel data.
I am using suiteCRM 7.7.6.Sugar Version 6.5.24 (Build 509)

Any help would be appreciated.

Prafull Satasiya

i am looking for the same, can anyone help