Okay, could you tell me what sort of a day you are aiming for. It is best to keep it to 12 -12.5 hours max, so 6.30am -6.30/7 pm? or is your day 6.30 - 8? Because that might be too long.
One point that stood out to me was that the last nap is from 4.30 - 6. (is that the last nap or are you doing another CN at 7?) That is extremely restful and he definitely would not be ready for bed an hour later. Taking into account the good naps through the day, and this last long nap, I feel that he is under tired for bed and that is why you are getting so much resistance. I think that all babies have a period of the day, generally the evening, where they are more awake & alert.
Typical Amounts of Day and Night SleepI understand that the 'usual' routine outlined by Tracy won't be suitable since you have another LO. She says to aim for 3 naps + a CN of 30/45 mins. How would you feel about capping that last nap at 45 minutes and then putting him to bed between 6.30 & 7?
I hope it is not a case of day sleep robbing from night sleep and these being UT wakings as he doesn't seem to have much A time through the day. What do you think?