collapsing plot lines

All,

When plotting a group data object, is there a way to have the plots
of all the groups collapsed onto one plot, i.e., instead of 
separate panels as would be produced from example below?

grouped.data.example <- groupedData(Y ~ Time | Patient_no, 
	data = example.frm)
plot(grouped.data.example)

cheers,
dave
ps - I'm on windows