Originally Posted by
craigthemif
Many of the European flights operated by regional jets use the M gates. (especially those routes with lots of connecting traffic to/from long haul)
Since you don't pass through passport control into the main area of T4S, you can't use Velazquez.
As long as OP can exit and reenter the Schengen Area, I don’t see why she could not go through exit passport control, stay at Velázquez lounge, and then return via arrival passport control back to the M gates. This would be allow better time management than having to leave Dalí and take the transit to T4S IMO.