You, see a discussion about this subject always ends in a big mess.
But, about the alternate route, I totally disagree with Edi.
You may have a point from a conceptual view.
But if you look at it, just from a rule point of view, the old rule is horrible. You get many issues, when foreign fleets are involved in the convoy.
See also the DPTG:
"Where more fleets than necessary cooperate in a convoy, the convoyed army may find two or more alternate convoy routes available to it. This is acceptable, but an army prefers, if possible, to be convoyed by its own countrymen only -- that is, only by fleets belonging to the same Great Power the army belongs to. (This does not mean that an army prefers to be convoyed by fewer foreigners rather than more -- only that it prefers to be convoyed by zero foreigners, if possible; if impossible, then the army
sees two foreigners as no worse than one.) For this reason, if there are sufficient cooperating countryman-fleets to complete the convoy without foreign fleets' help, then exclude all foreign fleets from the convoy, cancelling the foreigners' convoy orders."
And even more you have to consider:
"After refusing foreign cooperation if possible, an army may find that it has an extra cooperating fleet it could not use even if it wanted to. This is a fleet that is not part of any remaining route the army could follow to its target. The fleet's convoy order is superfluous; cancel it.
This Step 1 cares only that orders to convoy and to move by convoy are properly consistent, that convoys trace correct routes, and that foreign cooperation is declined where possible. It does not care whether a convoying fleet is under attack, nor whether some unit contests the convoy's target province. It also does not care about support of any kind."
If you allow the alternate route, all text above, cease to exist. Given the minor tactical implication, I would say, please have some mercy with the people that write adjudicators.
Even with the DPTG text, you still have remaining issues. Suppose you have a convoy order that can be used in a convoy, but is not required in any of the routes (you can remove it from any route and still have complete convoy). You can argue, that those convoys should also not taken into consideration (not easy to program correctly in an adjudicator and I need about 10 or 20 additional test cases in the DATC to cover it all).
An alternate route, is often not good from tactical point. It is often better to let one of the fleets support (or doing something other useful).
There is an issue of unwanted alternate route. If you don't want the convoy to succeed, when the convoy is disrupted, the unwanted alternative, can let the convoy succeed. Okay, that is true.
But with the old rule, you can have two foreign fleets both have the possibility to convoy. If one is almost certainly dislodged, it can give an unwanted convoy, to disrupt the convoy.
So, those two situations cancel each other out, as argument before or against.
New rule is a big simplification.
Regards,
Lucas