I got 4000 limitation from below link, LineItem section.
Yeah, in the doc you provide, it says
There is a limit of 100 line items per campaign and 8,000 active line items across all campaigns.
But 8000 is still too small for our business. Our business traffic more than 200k LineItems to Yahoo and 100k LineItems to Facebook in the past months, and we are still growing very fast.
Do we have a way to break the 8000 lineitems across the Ad Account? Or can we just create multiple Ad Accounts like Facebook?