On behalf of..?
How do you say it? I put down se extiende a...
4 Answers
... the following certificate is hereby issues to........
De parte de...
It sometimes depends on context, but one of the meanings and usages of "por" is to express that something is done "on behalf of" someone else.
Vine por Juan. Vine en nombre de Juan. I came because of Juan. I came on Jaun's behalf.
Vengo en nombre de Juan is common as well as Vengo de parte de Juan.
Vine por Juan means "I came to see (or to fetch) Juan."