I actually ended up with using a global variable. On main form i have a timer repeated every 1 sec (sort of heartbeat), so on second form on closing, i put
Then on timer callback on main form, i have the following
if (global_Reload) then begin
global_Reload := false;
LoadIPAddresses;
end;
Bit hacky but works. I guess zvoni way is best to have public procedure on MainForm and call it from second form. Ill give it a try later. Thanks all.