coelacanth, the waiting period is 3 months and not 6 months.

rest of the steps are right.

u have to get a medical test done for ur wife and child (at medical commision in abu hamour). then after 3-4 days u can go to any visa center (gharaffa or meseimeer) and get the visa extended.

i suggest you wait for a week if you have time as sometimes the medical results take more than 3 days.

charges are QR 200 per passport per month(age doesnt matter)

btw, one more thing. Over stay is charged at QR 200 per day per passport.