Warwick XL Internal Roof Lining

On my recently acquired 2014 Warwick XL have noticed that the internal roof fabric at the over cab area where the cabin roof cladding meets the wood panelling is sagging slightly in one area, the original glue is still evident by feel but no longer holds the roof lining completely in place.

Apologies for the very poor quality picture attached, however, the sagging roof lining portion can be seen in the centre.

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Can't feel any wood behind the sagging area so certainly do not wish to utilise any form of trim retaining screw, would not want to end up with a hole in the roof !

Wondering what would be the best remedial action, suitable glue, double sided tape etc ?
The bonding required would appear to be roof "fabric to fabric" as far as I can see, difficult to get a clear view even with a mirror as the gap is pointing forward, glue certainly was the original bonding medium.

I can "shutter" the sagging area with wooden laths while suitable glue bonds.
With the bedding coming in and out of the storage area on a daily basis I would like to get the "droop" repaired in case it should spread further, any suggestions welcomed.

Hello,
       Would it help to send a picture to AS and ask what's behind the sagging material and your chances of a neat fix? They can only say no they can't help or yes they can. Bet you're not the only one with this problem,
                                                               Good Luck, Smithee.

@Smithee:

Thanks for your response and advice, much appreciated.

Have taken your advice and sent a quick query to A-S with the image, will see what that produces.

In the mean time, advice from anyone with a similar issue welcome.

Well, no response to date from Auto-Sleeper, not even the normal, automated e-mail acknowledgment, disappointed.
Any suggestions from forum patrons still very much welcomed.

Have also become very much aware of the long standing and widely documented engine bay water ingress issue via the windscreen scuttle which I would like to get sorted before undertaking any serious touring, have ordered up the recommended bits to hopefully address this as per the forum suggestions.

Again, somewhat disappointed that the dealer did not see fit to address this before delivery, as the main Fiat dealer for the area and a major motorhome supplier I can't believe he would not have been aware of this long standing issue.

Starting to regret that we parted with our immaculate, 2015 Hymer B-524 "A" class which was 100% ready for the road, hopefully things will improve.

Edit:
Typo error, should read "2005 Hymer B-524"