Colo,
Remember you will be on the FO salary for a long time. There are some 1700 FOs on the list in front of you.
Your fourth child is not covered by EK for education nor for tickets home. The fourth child costs more for medical cover, yet receives coverage less than the first three.
You might as well consider your salary reduced by Aed 5 to 6k per month just to educate and get this child home once per year. That doesn't include the Aed 2 to 2.5k per month (bus costs extra) to make up for the shortfall in education costs of the other three.
As SOPS said. Think long and hard about this.