Recreate external data groups on a test LTM to test another LTMs

If I try copying the external data group files from the prod LTM The filenames look like this

%3ACommon%3Adatagroup_file_110335_4

when importing I get the error

0107169a:3: The data group external file (/config/filestore/.stage_d/24_d/Common_d/data_group_d/:Common:datagroup_file_20082919_1) has an invalid format, line: 2.

Then I tried editing the files leaving just the first one line - that seems to work

but then if I try loading the prod LTM config ....

01070712:3: Values (/Common/datagroup_file) specified for value list (/Common/datagroup): foreign key index (file_FK) do not point at an item that exists in the database. Unexpected Error: Loading configuration process failed.

still can't get the full config to test - only if I comment out the data group file line will the config load successfully, but with broken external data groups .... maybe I just have to delete them and recreate them, but I have to find all the references in iRules to deal with ...... not good.

} ltm data-group external /Common/datagroup {

type ip

}