Hi,
> The Wide role is possible for the Theatre’s internal speakers
This is not correct. The side-firing OR the "wide" virtual outputs can be assigned to have any speaker role, but a "wide" speaker role is not one of those options.
I realise that there may be some confusion caused by the naming of the virtual outputs as "wide" instead of "surround", however, this was done so to overlap of the input channels's names (the Speaker Roles) with the output channels'. You can blame me for this.
If you are placing external loudspeakers next to the Theatre (near the optimal locations for the Left Front and Right Front loudspeakers), then I would recommend that they be given these roles, and that you either choose the Centre output only for the Centre Front Speaker Role, OR use all three front-firing outputs for Cf (with some tweaking of Speaker Distances and Speaker Levels to pull things inwards a little as described in
link)
If they really are out farther (say in the region of ±60º instead of ±30º) then I would recommend setting them to Left Surround and Right Surround roles, but lying to the Theatre and telling it that these are slightly closer than they actually are. Duplicating the roles with the actual Surround loudspeakers will help to tie things together, but lying about the distance will help to pull the image back slightly.
It may be counter-intuitive, but if your input is primarily 5.0 or less, then (I know I know... it's weird...) it is worth trying setting the loudspeakers in your wide" locations to have "Back" speaker roles. It might not work - and it certainly won't for 7.x.y materials - but for upmixing it isn't necessarily a crazy idea.
I've done a similar setup where I had an Eclipse and two Beolab 50s as a front "3.0" system where I set the internal outputs of the Eclipse to play (from left to right): Left Surround, Centre Front, Right Surround (and the 50s playing the Left Front & Right Front, of course...) This worked well.