oh wow, well lots of things going on right now (ugh molars, we had lumps and bumps and the grumps since christmas, and just have one through i think i saw for the first time today) and the week 55 ww was a fussy one for us, it will pass!! i think long nw aren't unusual for that age, we didn't really have any, we just had more nws, and multiple nf which may have helped prevent them for us (sigh!)... Hmmm. I am not a wiwo expert, but yeah you walk in, pd and say sleepy phrase and leave, and go in if it's an i need you cry. Your lo might get more upset when you leave, but they should learn you're there if they need you. It's important to let them have a chance to settle themselves, I have to hold back a bit from running right in again! I was prepared to do it as long as i needed to, and i guess you need to monitor those cries to determine how often you're going back in. if it's stop start i don't go back in, i'll make it worse!
Wiwo is for LOs who were independent sleepers, rather than gw, where a lo might need you more as they haven't been an independent sleeper yet. You know your DD best though, if something else will work to get you through this patch, do it! Otherwise if it's not happening, give wiwo a try, and be prepared for possible crying. Ummm it can't be nice to walk the street at night with DD, and if it's anything like my place you'll be eaten alive by mozzies!
Ps your sister must be awesome!! Lol growing up i constantly got 'that's a weird name, how do you spell that'... Now there are stacks of variations!