Last question...at 10 mths old, is CIO my only option?

I did healthy sleep habits, happy child with my other 2, but they were much younger.

Ella is still co-sleeping much to my disliking.

We've tried CIO a couple of times just were not consistent with it. Her morning nap we can but her afternoon nap coincides with DS nap and if she screams, he won't go to sleep.

Same with bedtime...how can I do CIO without disrupting the sleep routines of the other 2?

Is there anything else I can try to get her to sleep in her own crib?

Re: Last question...at 10 mths old, is CIO my only option?

i have no experience whatsoever but i'll just make a suggestion.
if you really need her in her own space which i can understand i would do it soon as she is really getting older now. i understand you have 2 others to think about. are their rooms that close that they will hear? do you have some sort of white noise for either room to drown out the cries? can you stagger their sleep times? or you might just have to have a string of unpleasant nights to get to a better place. also, you might be surprised that your DC sleep through your DD's cries. last week we had VERY loud construction going on in our house and i though my DD would never ever sleep through it. i was amazed that she did. in addition to a very loud firework show next to my house. sometimes they are not as sensitive as we think, but i don't know your kids and yes, hearing their sister cry might affect them more so..i have only done CIO successfully do i don't know what other methods to try.
but either way, good luck and i hope you get everyone in their own space soon!