is it possible to do multiple sd -wan in one vdom ?

if you dont want to split them to seperated vdoms,  you should disable sdwan feature and create firewall policy from lan to seperated wan interface

org1LAN=>wan1

org2LAN=> wan2

you can also enable sdwan, and split one of the interface out of sdwan members, then create seperated policies for this

Hi adminuniscan, 

You can look into sdwan zones: https://docs.fortinet.com/document/fortigate/6.4.2/administration-guide/942095/sd-wan-zones

Thanks, 

Shahan

I think I found the answer to my question, it will be sd-wan rules

Hi adminuniscan, 

You can use sdwan rules to steer traffic towards required sdwan interface: 
https://docs.fortinet.com/document/fortigate/6.2.0/cookbook/716691/wan-path-control

However, please be aware that if wan connectivity fails via one organization, you have firewall policies in place to deny traffic via other sdwan interfaces. There is implicit allow rule which might match at the end incase of issue. So it would makes sense if you use sdwan rules in combination with sdwan zones and ensure that firewall policies are in place to deny traffic. 

Thanks, 
Shahan