Office VBA application add-in load / unload order

I've been doing some testing to try to ascertain what algorithm the Microsoft application add-in loader uses to determine the load order of VBA add-ins. To test it, I created two very simple PowerPoint ppam addins with two procedures in each.

Option Explicit

Sub Auto_Open()
  MsgBox "AAA is loading"
End Sub

Sub Auto_Close()
  MsgBox "AAA is unloading"
End Sub

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Option Explicit

Sub Auto_Open()
  MsgBox "ZZZ is loading"
End Sub

Sub Auto_Close()
  MsgBox "ZZZ is unloading"
End Sub

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When I load these and restart PowerPoint, I see the AAA loading message followed by the ZZZ loading message and then when I quit PowerPoint, I see the corresponding unloading messages, AAA first followed by ZZZ.

Given that there is only one occurrence of the add-ins in the registry, for example:
HKEY_USERS\S-1-5-21-1654165938-2830638315-1088483835-1001\Software\Microsoft\Office\15.0\PowerPoint\AddIns\Add-In AAA
AutoLoad = 1
Path = Add-InAAA.ppam

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there appears to be no record of the order in which the add-ins were installed so is it as simple as an alphabetic order as indicated be the above? Is this a reliable detection method?

Finally, I guess the reader(s) will ask "why do you care?". The answer is that I want add-in B to be able to install updates to add-in A but this can only be done when add-in A is not loaded and locked by the file system.
LVL 15
Jamie GarrochSenior Technical Consultant at BrightCarbonAsked:
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Alexei KuznetsovMicrosoft Outlook MVPCommented:
No reliable method exist to detect this order. You need to use other synchronization methods, like checking locks by either using external files and/or Windows synchronization primitives like mutexes. Or re-think your add-in update logic.

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Jamie GarrochSenior Technical Consultant at BrightCarbonAuthor Commented:
Thanks Alexei. Those are good pointers and I do already manage mutexes so that is a good pointer in a different direction. I'll hang on a bit longer to see if there are any other contributors before accepting the answer.
Martin LissOlder than dirtCommented:
I've requested that this question be closed as follows:

Accepted answer: 500 points for thims's comment #a41060486

for the following reason:

This question has been classified as abandoned and is closed as part of the Cleanup Program. See the recommendation for more details.
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