for a given user, howto assign a client certificate. not create new

[jojothehumanmonkey]

hello, thanks, hope i am posting in the correct section of the forum,

"System: Access: Users", i click on a user named `user01`

at "User Certificates", i want to add an already existing certificate, i do not want to create a new certificate.
but only i see the plus button, with the text "create new user certificate"

just want to assign an existing certificate to a user.