Inform the person you're getting the new bird of why you're getting a second one. If they don't get along, maybe they'll agree to trade again...

If i got a male, could I control breeding if I watched the daily light very carefully or if they did breed could I remove some of the eggs so they only had 2-3 chicks? Do they breed all year or only in the spring?

You can keep the hormones under control with most birds but not all, and replacing real eggs with fakes will definitely control the number of babies that hatch. Cockatiels are opportunistic breeders - their desire to breed is strongest in the spring but they can do it at other times too.

Darn little hussies!

Good idea, if I decide to get a second bird I'll do that.

No need for me to inform the breeder,
she is a friend and I've been waiting since my last 2 died... Oct & Jan.... the time s right now for me to have another...Im only having one tiel...