On the left under Project selection, select a project and then on the right, under Edit project, select the Links tab.

PARTproject -> Edit project -> tabbed page Links

In the dialog area Links to parts, click on the button New .

-> An Explorer window is opened.

Choose the desired accessory part and confirm with Open.

-> The accessory part is entered in the dialog area.

Update the index and open the part in PARTdataManager.

In the docking window Links, select the list field option Accessories.

-> The part determined as accessory in PARTproject is displayed.