You can convert a family you made in-place into a stand alone family file.
Open the Project containing the In-Place family.
Select the family and hit Edit In-Place tool.
Select all of the elements in the family.
Group all of these elements using the Create Group tool. Give the Group a name.
Make sure the Group is selected.
(stay inside the in-place family - do not Finish Editing)
Go to the 'R' button (Application Menu) - Save As > Library > Group
You will notice that the filetype is .rfa (it is .rvt when normally saving a group)
Save the Group in a your project family folder.
Finish Model tool to close In-Place family editing.
To replace the In-Place family just delete it and insert the new family.
(the group you made lives inside the In-Place family so gets deleted out of the project as well)