Seems like there are two questions being asked here: 1) Can I combine my miles with my friend/family member, etc if we fall short of the amount needed to book a ticket? and 2) Can I use two separate accounts to book tickets so we can be in the same PNR to enable us to share elite benefits (free bags, preferred seats, etc)?

Answer to number 1: No. The only way to "share" miles is to transfer them from one account to another through the link on www.alaskaair.com. This transfer is not free and is basically done by points.com. Barring a glitch in the system (which is rare), the miles post immediately.

Answer to number 2: Yes, but not online. An agent can help book using multiple accounts providing they each have enough miles for one ticket. This means there will be a phone fee for non-Gold members and that these reservations may not be changed on alaskaair.com. The reason for this is because the website verifies your account information when you log in - which you can only do with one account at a time - whereas an agent can verify everyone's information individually. Agents will not generally offer this option so you have to ask them to do this for you. Also, keep in mind that just being in the same PNR does not mean the non-Gold members won't have a change fee if the tickets are changed/redeposited - they will unless their ticket came out of the Gold member's account. Only full flex awards and awards redeemed from a Gold member's account qualify for the fee waiver.

Now I am by no means an expert in this and, as always, the information I provide is subject to change at any time.