In form A create a method as below
[ExtensionOf(formStr(SalesLineOpenOrder))]
final class MCOSalesLineOpenOrder_Extension
{
public void RefreshSalesLine()
{
SalesLine_DS.research();
}
}
On closing of form B write the following method :
public void close()
{
super();
if(formHasMethod(element.args().caller(), identifierstr(RefreshSalesLine)))
{
FormRun formRunObject;
formRunObject = element.args().caller();
formRunObject.RefreshSalesLine();
}
}