It has Nicky 
We had lots of crying from DD going to sleep until she was 7 weeks. Then 'getting' that she could suck on the dummy (which happened when she was about 7 weeks, after much hard work) was like a magic switch. Nights and all naps a million times easier.
I've taken things slowly, not pushing DD to anything she is unhappy with. She never cried on going to sleep. This meant a gentle transfer to cot sleeping with patting at around 5 months, then patting changed to hand on chest until she was asleep, then me lying next to the cot (on my bed) until she was asleep, then waiting by the door. Now, at 11 months old, I can put her in cot with dummy fully awake, leave immediately an not hear a peep from her. It's taken gentle time though.
Regarding toddler siblings - I don't have that problem so much this time around (my other three children are 11, 10 and 6 so are all at school). I have had the baby & toddler at home before though.
My vote is for as much noise, light and chaos as possible around that sleeping baby. I fully believe light/deep sleeping is down to nurture, not nature. I think you can teach a newborn baby not to be a light sleeper by having them sleep in noise and goings-on during those early months.
My eldest two are 14 months apart so I had to embrace the 'little baby and big baby' chaos at home. DC2 is the deepest sleeper I know. I used to put him to sleep directly under an overhead light, by the window, next to the TV, in the living room while DC1 played. Because he could sleep with all that going on, when he went to bed at night in a quiet, dark room he slept very, very deeply and always has done which caused a problem with bed wetting, but that is another story.