Co-sleeping Advice & 7 Month Old

You know, every kid is different. It sounds like your little one falls asleep easily and quickly for naptimes alone in his crib...but it is more difficult at night to co-sleep even though you know he is super tired. Maybe he is a solo sleeper. It sounds like you and your husband enjoy the co-sleeping, which is fine...but if your little guy isn't getting the sleep he needs, maybe he would do better solo.

Listen to cues from your children. If you are good with the co-sleeping..and that is what they are responding positively to...then go for it. But if they want to sleep alone...or sleep better alone...then follow that as well.

As parents, our job is to do what is BEST for our children even if it isn't exactly what we want.

Divide and conquer. One of you will have to snuggle and lay with the 5 year old while the other is with the baby.
How are naps during the day? At 7 months he should still be taking two good long naps, avg. 2 hours each. You should be able to put him down for his first nap just 1.5-2 hours after he wakes in the morning, have a 3-4 hours gap and then back down for 2 hours. The better baby naps, the better they go to sleep at night. Maybe he needs another nap, or a longer one during the day. Increase length by incrementns, putting down 10 minutes earlier at time, or not going into the room immediately, but let them fuss for just a few minutes to see if he'll settle down for more sleep. We cosleep here at my house too. We just barely moved our 14month old into the other room to share with sister.
My little one slept on the 9pm-7am schedule for a while...now it's 830-730. But naps are a must! If she misses a nap, every consecutive sleep time is more difficult.

It sounds to me like you should try putting him in his crib at bed time. I'm guessing that you and your husband don't go to bed at 7:30? Do you get to bed at 9?
Does your 5 yr old sleep in your bed, too, or do you snuggle with him before he goes to his own bed? You can "snuggle" your 7 month old before you put him in his own bed, too, just not in his crib with him. I always loved the quiet moments in the glider, rocking my babies before I put them down at night.
But that said, I'll tell you that I"m not a fan of co-sleeping. I sleep so much better without a baby in my bed! So I work hard to get them out. That's my preference. Maybe it's your baby's preference now, too.

Have you tried going through the naptime routine at bedtime? He might be able to go to sleep the same way. Also consider pushing the nap to an hour earlier, or making it a bit shorter.

You and your husband may have to take turns snuggling with your 5-year-old at bedtime so the other is in with the baby. Or bring the baby in with you and all snuggle together for a few minutes.

He also could be teething or just going through a growth spurt that makes it harder to settle down. Go with the flow, but also try to adjust the flow if you can so that it works for all your needs.