Co-sign and Vouch for

Co-sign verb - Sign jointly.

Vouch for and co-sign are semantically related. in pledge topic. In some cases you can use "Vouch for" instead a verb phrase "Co-sign".

Vouch for verb - To declare (something) to be true or genuine.

Co-sign and vouch for are semantically related. Sometimes you can replace phrase "Co-sign" with "Vouch for", this terms are similar.