Send friend requests from your accounts.
Paste tokens and the users to add. Every captcha on the way is solved for you, and you pay only for requests Discord accepts.
How a friend request goes
Check
Each sending account is checked first. A dead or locked one stops there and costs nothing.
Find
A user ID is turned into the user Discord knows.
Add
The request goes out, and any captcha Discord asks for is solved.
Confirm
The account is checked again afterwards, so you see whether Discord kept it.
One request per account: Discord signs an account out on its second friend request, and often a fresh account on its first. The token stops working until the account logs in again.