Lots of the typical sleep trainer advice falls at this hurdle. It's all very well saying best habits develop if invest the time to get baby cot napping from birth without any props. Nice ideal and I'd certainly do this with my first, but I have four children so life is very different when all of my children have equally valid needs.
So firstly - dummy
I wanted my children sleeping independantly (ie not on/with me) but I wasn't prepared to have them crying in order to achieve that. Shush Pat, PUPD, and method you use for this is likely to involve some crying unless you have a dummy established well and early. A baby actively sucking is both soothed (natural sucking reflex is calming) and physically cannot cry. It makes independant sleep much, much easier to achieve even in the neediest, high needs babies.
Dummy is central and key to my entire parenting ethos (which is centred around getting baby to sleep independantly through gradual withdrawal without ever letting baby cry for even a moment)
Second - bouncy chair
As you have eluded to, when you're in that phase of baby having lots of naps a day, while cot naps would be brilliant it's not feasible with a toddler around too.
I started cot naps only once daytime naps had extended past 90 minutes and progress at settling baby in the cot at night was much quicker, 10 minutes or less. For me, that came around 5-7 months old. So until then daytime naps in the bouncer.
Benefits of the bouncer:
- rhythmic movement is an extra help to get baby to sleep (as well as dummy) given that pressure to sleep is less in the day
- independant sleep. Establishing that for every sleep time, every day, from newborn baby will be put down wide awake in a place to go to sleep and will be helped to go to sleep there.
- the no hassle settling technique (bouncer by your feet as you sit on sofa, foot bouncing) means you are totally free to do other stuff while settling baby. Playing and interacting with toddler freely from the sofa or just watching tv and drinking a cuppa.
- the no hassle settling method also encourages regular naps with less awake time. There's no dreading settling baby
I'd feed baby, put baby on floor to play (while I do household chores) and by babys very first grumble put into bouncer and getting to sleep. Thhi leads to very frequent naps. More sleep equals better sleep.
- extending naps is easy, just restart bouncing to lull back to a deep sleep if you notice any light sleeping. Likewise if you know baby is a bit overtired, keep bouncing gong for longer through the nap to keep baby sleeping. Otherwise over tiredness causes light sleeping and waking easily.
third - sidecar cot at night
Bouncy chairs are great, but not suitable for unsupervised sleep at night. A sidecar cot allows you to settle baby in a similar way to cosleeping, but extract yourself afterwards and for it all to be done in the cot.
The swaddle is useful for newborns, with a dummy, and I would always use straight from the delivery room. It helps with establishing independant sleep (baby being put down to go to sleep). I only wouldn't use a swaddle for a baby who will easily sleep without it. Any challenge getting to sleep and newborn would be swaddled.
Sidecar cot means you can feed, wind, swaddle and put baby down (swaddled dropped in the 2-5m range usually). Then dummy and cuddle in the cot to sleep, extracting myself once asleep.
Up to 6m ish these in-cot settling would only happen at my bedtime (10-11pm) and through the night. All other sleep in bouncer downstairs. As such, toddler not around in these early months during cot settling. There's no time pressure on how long cot settling took because I'd be in bed next to the cot anyway.
Once naps start extending past 90m in the daytime and baby is sleeping through the entire evening in the bouncer (all hspoens around 6m ish), then I start cot settling for all sleeps.
At that point I have had 6 months to establish in-cot settling at night and will have been gradually reducing the amount of help needed from me.
finally - firm hand on chest
I would not describe what I do as shush pat. I aim for stillness and quiet for cot settling. By its nature patting is not stillness and shushing is not quiet. I would use a little shushing or patting for a few seconds, with the main purpose to refocus baby on dummy sucking (which stops crying and comforts). As doon as dummy sucking is happening, I go back to still, quiet but close.
So newborn I might cuddle right in to cot. By about 2-3 months I would expect to just need my head next to baby's, hand on chest and dummy inserts (all done without me really waking up in the night). By 4 months I'd expect to just need to dummy reinsert then lie on my bed next to baby with my hand on chest. It's around this time the side goes back on the cot.
Therefore by 6 months when daytime cot naps start, a lot of gradual withdrawal progress will have been made towards independant cot sleeping. I would by now be putting baby in (non sidecar) cot with dummy, hand on chest and waiting still and quiet for baby to go to sleep. It would usually take 5-10 mins, more than 15m and I'd be concerned something was wrong.
As for other children, well by this time naps are longer. So the payoff for allowing mummy 10 mins to settle baby is 90m 121 time without baby. I'd often time naps around other child being busy - a meal or snack, a special program on tv. Then once baby asleep make a fuss of 'big boy/girl' and enjoy some quality time.
increasing independence as a parenting ethos
My philosophy in gradually increasing independence is not a slerp sleep training method, it's a parenting ethos. It does not stop at the baby months. I use in non-sleep contexts through the toddler years. I still use the ethos with my 8 year old, 11 year old and 13 year old. Always encouraging safe and gradualmy increasing independence, rather than dependence.
It's reasonable to expect toddler to be alright for up to 15 mins in a safe room without you, as long as engaged in sometime. I'd explain where I was (putting baby for a sleep) before going. I also would also do other things that meant toddler was entertsining him/her self, as practice regularly. Have a shower while toddler plays downstairs, for example. Cook a meal in a room separate to toddler. Put clothes away upstairs while toddler is downstairs.
There is no reason (and I believe no benefit) to a toddler being dependant on parental presence and engagement at all times. Confidence when being independant can be taught in a safe, she appropriate way right from birth for the first 20-odd years of a child's life. I think. Certainly in a baby and a toddler. That's just my parenting philosophy though.