missrose, i would say that if she is happy to suck her thumb then let her, my ds4 sucks his thumb and it was a GODSEND with sleep, if they are too sore to suck she will let you know. but yes they do grow out of suck to sleep but may need a bit of help along the way, my way was to let them get sleepy and then gently encourage them to fall asleep with me lying next to them adn patting them etc, i could usually tell quite quickly if this was going to work and i never 'pushed' it as an issue iykwim? as they do get their gradually with a bit of encouragement. how old is your dd? i think the suck to sleep thing is probably what most babies need until 6mths ish tbh and i didnt really start trying to stop it till nearer to 7-8mths and i got dp involved in bedtimes so he would lie with them once they were very sleepy and would pat/shush etc, sometimes this invovled a bit of crying but not loads as dp and i are both softies and cant cope with crying 
so dd had a really SHITE night the night before last, if didnt get any bigger chunks bigger than half an hour and was awake from 4am replacing the dummy, i was in tears in the morning and i thne went back to bed leaving her with dp.
it made me question whether letting her have the dummy is a good thing and maybe we should just lie with her and shushh pat so she got used to going down at bedtime without it (was going to let her have it for naps) but at 21wks today, i think she is too young? and she WOULD cry and i dont think i can let her as she is too little? :(
anyhow last night was much better apart from a mega puking session at midnight (she has a cough again) and then she slept till 4:30 and fed and went back to sleep till 6:30 andthen i had to replace the dummy a few times between then and 8am when she woke!! thats the latest she has slept for AGES!! so that makes me think i can cope on nights like that.
i think at the moment my plan is to get to 6-7mths get her established on solids and move ds4 out of our room and then alter her bedtime routine (at the moment she sleeps for the evening in the pram in the livingrm) and start putting her to bed upstairs with a routine of change, feed, cuddle and down and we may try to do that without the dummy and do shhh pat, so that she at least goes down in the evening without the dummy? but we shall see it reallly depends on how our nights go, i can cope with occasional crap night ansd some not so good ones, but if they consistently become shite then we will have to do something before then. but i really hope we can just ride it out and she will leanr to find the dummy herself? BUT to do that we would have to stop swaddling her and at the moment thats not an option as she would just knock the dummy out all the time
or maybe if we get desperate we would go cold turkey with both dummy and swaddling at 7mth ish? but i REALLY dont want to have to do that.
RAISING it sounds like he is ready to go down later, how old is he? we had been putting dd down for her nap 2hrs after first waking but recently its been more like three hours as she gets older and able to stay awake happily. IF he is happy in his cot then thats fine but if you are constantly reassuring him and settling him then maybe try keeping him up longer, it may be (like iwth dd) that some of that time has to be cuddle time, quietish activites ie read to him etc adn then when he goes down he will go off more easily?