Question: If one of them requests that I convey their ‘salaam’ to someone I know, then am I obligated to do that?
Response: He has entrusted you with a request, so you must fulfill it. When he said:
convey my ‘salaam’ to such-and-such
…and you replied:
yes, I will convey it in shaa.-Allaah
…then it is required of you to fulfill the trust of [conveying] the ‘salaam’, and carry it to the [intended] recipient and say:
such-and-such conveys his ‘salaam’ [to you]
 The greeting of “as-salaam ‘alaykum”.
[2, 3 and 4] Or words to that effect.