Only ones I actually recall being referred to as sibs in the TV series were SunStreaker and SideSwipe.

I don't agree with quite a few of the things written into DW's second story arc...Magnus/Prime being among them. I don't really consider it canon unless Hasbro comes out and says "yes, Prime and Magnus were brothers".

in g1 sunstreaker and sideswipe were brothers (something to do with lasercore's being spilt between the two.

 

bearing this in mind it could be said that in beastwars dinobot 2 and rampage are brothers "i need your new half-brother for..."

 

rid, magnus and prime were brothers but extending that to the original universe is confusing.

 

 

speaking of sideswipe and sunstreaker i'm suprised there have been no fan fics about sideswipe being saddened and infuriated by his brother's body being stolen

Then, were the Dinobots bros?

No, I'd have to say they weren't brothers.

 

Thundercracker/Skywarp/Starscream in my opinion were brothers, as were Rumble/Frenzy, and Eject/Rewind.

 

The Battle Chargers (Runabout and Runamuck)

Dont forget RiD's Autobot Bros.

 

Some how Arcee is Rattrap's GreatAunt.

Some people consider Soundwave's cassettes to be like "family" to him (our own DC's old sig even had a joking version of that). I'd agree that they seem to be close -- Rumble almost seems to look up to Soundwave as a father figure. I could see why they'd all be considered part of a family more than the other robots.

Then that would make the combiners family as well.

I don't see the Combiners as a family. Most of the Combiner groups bickered amongst themselves a lot, even the Aerialbots. They probably saw themselves as little more than a group whose purpose was to turn into a giant robot to go up against their enemy's giant robot. I doubt they had a sense of "family" for the most part, especially the Stunticons (who disagreed on EVERYTHING).

i usually explaine the concept of brothers by using the spark retcon. maybe sometimes when a spark is created, it has a significantly above average energy level so as a resault, it splits in two(and in rare cases, three) to keep from overloading.