The Dornish Marches Ownership

[Maester Saramello]

Tyrion said in ACOK that, along with betrothing Mycrella to Trystane he would give him some castles along the marches. Now, considering Highgarden would not like it very much if they had to give their marches, and Randyll Tarly is still Lord, I'm guessing this was taken from the Stormlands. The Stormlands surrendered unconditionally after the disastrous battle of the blackwater. So is the stormlands marches, nightsong and those other castles, now in(or are technically in) Dornish control? 

Also food for thought - The Stormlands is one of the least populous kingdoms, very diffused according to the wiki. It is relatively small and can raise roughly 35,000 men. If the dornish marches were taken, this would effectively neuter them, leaving them around 30,000(if you want to argue that the dornish marches can't field 5,000 men, look at Randyll Tarly).