Here's a score we prepared earlier (and played last year). It's from a string duet by Haydn, and we adapted it for the flute. It's quite easy to stick together as the rhythm is mostly identical in both parts, and the parts individually are grade 3-4 level I would guess.
Next up is an adaptation of Johann Nepomuk Hummel's trio for piano, cello and flute in A major, op.78, which is essentially a set of variations on a Russian folk song called "Beautiful Minka." As the piano is quite dominant in this work and we don't have a pianist in the house, this one involves quite a bit of rearranging. We did just the theme last year, and I have now added one of the variations. Work in progress here:
Russian theme & variations