Many to Many Self Join; question about portals

[oilcan]

I have a situation where I have made a join table in between two TOs of the same table. The table being joined to itself keeps records of cell line Batches. The many to many self join is necessary because sometimes multiple batches of the same cell line might be pooled together. The join table in the middle holds the associated batch numbers, to be assigned and viewed in a portal. The join has two keys, the primary key assigned from the record in which the portal entry is being made, and the second key is the value which is entered in the portal row, the id of the associated batch.

I've set up a dwindling value list structure, and that works, but there are problems regarding how users can quickly tell if any given record is combined with other batches if it wasn't the record that these combinations were assigned from. For example let's say we are on the record for batch x. this particular batch x has been combined with batches a, b, and c of the same cell line. In the record for x, you enter the assigned pooling. The dwindling list works fine, i.e. you only see items of the same cell line, and an item is not in the drop down list in the next portal row after you have already assigned it. The problem is that once you leave record x and look at records a, b, and c, you cannot see the associated batches in the same portal structure, because the portal is linked to the key of the record that was used to enter the information. I could see making a second portal to look at info in the join table's second key, and it is possible I could settle on this or some other workaround, but for now let's say I wanted this same portal to display other records that the current record is associated with regardless of whether it's the record from which said associations were made...there's probably something simple I'm missing here, and I think it must deal with some RG wizardry. Anybody have any suggestions?

Oh, and we are going to start deploying on FM10 in a week or two, so FM10-only advice is acceptable :

Thanks

[comment]

Sounds very similar to this:

http://fmforums.com/forum/showtopic.php?tid/171427/post/182646/#182646