Attest and Co-sign

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

Co-sign and attest are semantically related In some cases you can replace phrase "Co-sign" with "Attest", this terms are similar.

Co-sign verb - Sign jointly.

Attest and co-sign are semantically related in pledge topic. Sometimes you can use "Attest" instead a verb phrase "Co-sign".