Something I've been pondering as ds2 is getting older (he's 6 now and quite sensible). DS3 is still a it young but this will become relevant to him in the future.
DS2 is now of an age where he can help me a bit with ds1. For example yesterday I was trying to cook dinner - and ds1 was upstairs. I know he's climbing at the dodgy windows all the time at the moment, so he needs constant checking. But I can't cook and walk up 3 flights of stairs repeatedly so I asked ds2 to run upstairs and check whether ds1 was climbing for me (he was, so I got him down).
This little routine/this type of thing can happen repeatedly - and ds2 did at one stage huff 'it's ALWAYS me that gets asked to do this'. Which is true it is. I would never ask him to go upstairs and generally watch ds1 because that would be too much responsibility for a 6 year old, and the consequences of ds1 falling through the window whilst ds2 played on his DS or something would be too awful.
But how much is it OK to ask a sibling to help. Obviously as he gets older there'll be more he can us with (ds3 too), so how much do you get them to do.
Other opinions/experiences welcomed as it's something I can't work out.