No problemo.
And since we are talking xfce4-terminal here I will add that many apps - including xfce4-terminal, thunar, and (I think) spacefm, will open with a unique role attribute. When using the Remember section of the WindowMenu, that role is captured. So for example, xfce4-terminal entry will look like -
[app] (name=xfce4-terminal) (class=Xfce4-terminal) (role=<Some Unique Text>)
since the role is unique, the xfce4-terminals will not group. Just delete the "(role=<Some Unique Text>)" from the line and all will be good. Applies to any app that does it.