PSA: Do not afk while waiting on a /remake to happen, or you may be counted as a leaver as well

If your ally is disconnected from the start and you're going to wait for a /remake, do not sit in base or way behind the turret and not participate.

A /remake will still be valid even if someone dies as long as the disconnection was before that, and if you don't do anything you may lose LP and be given a low priority queue as well. Continue playing the match as you would normally when down a player (safe, but keep playing).

https://support.riotgames.com/hc/en-us/articles/208754686--Remake-FAQ

CAN MULTIPLE PLAYERS BE PUNISHED IN A SINGLE GAME, EVEN WHEN NOT PREMADE?

Yes - if there are more than one inactive players (premade or not) they will all receive the penalties for /remake. This includes players who decided to AFK while waiting for /remake to appear - it's highly advised you remain active even if you know or think a player is not going to connect, or you risk receiving the penalties also!