In Whmcs 7 the Whois Server definitions can be found in /resources/domains/dist.whois.json.
To configure .UG whois, please add the following code
{
"extensions": ".SS,.ac.UG,.co.UG,.or.UG,.ne.UG,.mobi.UG,.info.UG,.go.UG,.me.UG,.sc.UG",
"uri": "socket://whois.SSnic.or.UG",
"available": "No Object Found"
},