Getting 5 month old to nap with a toddler around

[user1474565301]

My 5 month old still needs my help to get to sleep for naps. I'm desperately trying to put her down in the dark in my bedroom, drowsy but awake.
The thing is, my 2.5 year old seems determined to sabotage it every time. She stands at the bottom or top of the stairs, shouting, screaming, crying. Basically, being jealous and not wanting me to give baby attention instead of her.
I've tried ignoring it and carrying on with trying to get baby to sleep, but toddler makes so much noise, it's impossible.
What would you do?
If at all possible, I don't want to sit her in front of the TV 4 times a day while I get baby to nap.

some things you could try:

giving her a doll and letting her put that down for a nap when you put baby down

letting her play an educational game on phone or tablet, just while you are putting baby to nap. once you have done that, you can take her off it (Tozzle is a good app)

giving her a snack while you put baby down (only ones she cannot choke on like yogurt)