Hi Nausika,
The way I see it is, whatever works for your baby and you is best.
I cuddled my baby to sleep and then put her in her moses basket for 4 months, then she moved into her room, and I would go to her whenever she cried, and she got very used to me being there and having a feed, which meant she kept waking up 3-4 times at night.
Initially, I felt super comfortable with this, it was quite flattering that she loved spending her hours with me, and it felt easier to do this than to put her through any 'training' and I was happy to continue... my DH and I talked about sleep training (which incidentally, our mums didn't do with us) but couldn't bring ourselves to do it.
but then one night when she was 7 months old, at 2 in the morning, it just seemed to make sense- she'd had both boobs twice, had a clean nappy, and would sleep in my arms, but instantly wake up as soon as I tired to put her down, and it seemed to me that she wasn't really in a properly deep, restful sleep, if she could rouse that easily and right then we started letting her Cry It Out, with my husband popping in every few minutes to reassure her.
It took an hour and a half the first night, and at one point we were all 3 crying.
After 4 nights she was sleeping through. Still loved us in the morning, and really was full of beans and raring to go the next day.
Maybe becasue I was going back to work at 9 months, we were anxious about our own routine as well as hers, but it really worked well for us, and are all a lot more rested for it.
all babies are different, and you'll know what'll work for you. Try not to listen to the inlaws. Because they care, they say it with a lot of passion, but it isn't for them to decide.
I would never have been able to leave my baby to cry when she was 10 weeks, and probably not at 6 and a half months either, but now i'm glad that we did.
There are no rules. There ARE strong opinions on either side. Read as much as you can (lots on mumsnet!!) and do what feels right. That will never be wrong.
Good luck!!