Hi ally, just dropping by for a quick browse and a hello... I've been through what you're going through with my dd. after we got her sleep sorted I could see where I went wrong, and when we had our second child we proved that we went about it the wrong way the first time as we had success with him.
The first mistake you've made here is trying everything under the sun. It unsettles her to change her routine, so she just wants to keep going back to what she knows. What you need to do is choose a method of settling her and stick to it through hell or high water. For my dd I chose 'self settling' when she was 13 months old. This involved putting her in bed, walking out and letting her scream. I didn't go back in... First night she screamed for an hour, and kept waking in the night... I didn't go in. Second night she screamed for a half hour, woke a few times and cried for a short time overnight. Third night grizzled for 15 mins, went to sleep and didn't hear from her til morning. She slept through every night from then on.
I don't actually recommend what I did. It was horrible, and it happened out of desperation because I was actually afraid that I would hurt her if I didn't do something drastic.
When my son was born I had researched it and knew how we'd go about it. Because I demand fed I was getting up frequently to him when he was younger so I still needed to get him to learn how to settle... I used the baby bliss routines from their website (you have to click purchase and go through checkout, but they're actually free. Weird I know) then from there we would do his bedtime routine and put him into bed sleepy but awake. I'd listen to his cries and I wouldn't go in straight away.. I'd only go in when he was starting to get distressed... And when I went in I did the same thing every time. This was to go in, no talking or eye contact, put him up to my left shoulder and pat his back til he was calm again. The first night I did this maybe 20 times, and during the night too if it had been less than an hour since I'd fed him.
Because my resolve was not as strong this time I did give in a few times and fed him to sleep. Because of this is took two weeks before he started self settling with no upset. But... I never treated my giving in as failure, we'd just start again the next time he woke.
Babies like the SAME SAME SAME. So if you stick to a new routine eventually they will come to expect your reaction to be the same as what you've been sticking to, and that's what will then be comforting to them.
My son now sleeps through and we have no sleep issues in our house unless someone gets sick. We did have issues with what seemed to be night terrors with ds a short while ago but I did the research, asked questions and since then that has stopped happening too. (Thankfully!!!)
I will say though that if you choose to do this you should expect that on the first night or maybe two or three nights… you will not get any sleep. You have to just accept this and look at the long term and how this will not be forever. Learning to self settle never happens quickly, there's no quick fix and no miracle cure.. you just have to do the hard yards.
It's all well and good for you ladies to say it's natural and is less disruptive to the family… but in all fairness unless you've gotten to this point that ally is at then you DO NOT UNDERSTAND how debilitating this constant lack of sleep it. It's torture and it brings you to your knees mentally… Some people also seem to do okay with little sleep. I was not one of those people and absolutely did not cope with no sleep. So, with that in mind, it was NOT the best thing for my family to be feeding my dd to sleep every night because I could barely function as a mother, let alone be a good mother to my child. I would suggest that unless you have suggestions to support this mother with what she wants to do you should not say anything.
Good luck Ally!