p2x modelling in gnc, help me think, please

[Wm]

Background: I am a p2x investor, I like it, it is fun and may do some 
good to far away people and get me a better return on my money than more 
conventional investments ... or I could lose it all.  Ho hum.

the gnc point is how best to model a p2x investment.

my p2x investments involve hundreds of fractional (or more than 2 
decimal) transactions a month,  gnc doesn't like dealing with 0.0001 EUR 
because gnc takes the view than an EUR is meant to be used in chunks of 
9.99 and it is sort of right because there isn't a smaller unit of an 
EUR than a cent in coins and paper.

Detail: I run the actual p2x transactions through ledger-cli and get 
that to produce a journal per month (or whenever I'm interested) that I 
then enter into gnc, this works well in accounting terms but fails 
because gnc doesn't see the p2x asset as an investment for reporting 
purposes.

I thought the solution would be to make the asset account where the 
actual bonds live a Mutual Fund with a security of its own equivalent to 
1GBP or 1EUR etc as appropriate but that didn't work because the 
interest doesn't get recognised (possibly because I'm presenting the 
income as part of a tx with 8 splits to reflect the real world).

My understanding (which I now think might be broken) of how gnc works 
out what is an investment or not then fell apart.

In summary:

my modelling of p2x in gnc isn't working out as I expected.

how are other people dealing with similar modern or unconventional 
investments ?

is the concept of negative interest income really that unusual (it 
happens all the time in real markets so why don't gnc reports know about 
it ?)

maybe I'm behaving stupidly and I just need a clue <-- let's hope it is 
this :)

-- 
Wm