Help with Seedings and setting up comp

Hi there,

I've  created a 20 team knockout comp based in North Africa where Algeria, Morocco and Tunisia send 5 teams each, Libya, 3 and Mauritania 2. The first round of the comp is competed by 8 teams and I'd like to set it up as follows if possible, the two lowest seeded Algerian teams play each other and the same  for the two lowest seeded Moroccan teams and Tunisian teams. The last tie to be made up by the lowest seeded Libyan team playing the lowest seeded Mauritanian team. The other 12 teams enter in the second round.

I've tinkered with the editor (with seedings and valid cup draws) but whatever I do, I seem to get 5 Tunisian teams and 3 Moroccan teams in the first round.

Any help setting this up will be greatly appreciated. Thanks. 

Cheers.