NOPI has a good idea. Let's put it into rules immediately.
Discussion of the rules
The motivation for the teams to play games for the last places will be very low and I see no success for this idea. Instead, the 3rd place must worth something, the possibility to stay in the 1st division. I think that a small tournament with the 4 teams of the 3rd place can determine the two teams that will stay in the 1st division.
See Rules in brief...
For four and fifth placed're probably right. Let declare themselves admins if they want to play if their team is located in these positions.
Anastasakis,
I think it will be motivation. Why would lower ranked teams waited half a year to the new competition? It should enable them to more competition with other teams.
If the teams of the 4th and 5th place want to play for the final ranking of the places 13-20, they can do so. I suggest also that all the 4 teams of the 3rd place stay in the 1st division who will be consist by 12 teams. They will play for the places 9-12. I predict that the 2nd division will be very croudy because a lot of new teams will join the League.
This sounds OK to me. But again, which motivation would have teams to play if they know that it certainly enter the first division. Is not it?
How many teams will be next year, we'll see. Maybe it will be for two or three leagues. basis for the formation of the league, it will be good or bad result this year. New teams are going in the third tier, if they are big and strong maybe in second, but not at first. We should reward the efforts of teams this year
If there are 24 teams, will play in two leagues. If it is 25 or more teams, we play in three leagues. League can not have more than 12 members.
NOPI is right: 1, 2 or 3 divisions. 12 teams max. for the 1st division, 16 teams max. for the 2nd and all the rest in the 3rd division. The 8 more powerful entrants will join fo rthe next year the 2nd division.
Milan you are right for the motivation of the 3rd teams, but it is already a motivation to be 3rd and not 4th, so you can be in the 1st division, and it is nice also to be 9th and not 12th.
1st and 2nd division for next year is 12 first from this league in 1st division,rest 7 in 2nd division and the new teams for next year: 5 powerful in 2nd division and the rest in 3rd division.If is more new teams we put more teams in 2nd and 3rd division.
I agree with you. Let next year be 12 teams in the premier league, 12 in the second... about third division we think if there is enough cities. I am looked the site and not something a lot of groups representing cities, although it might create in the future ..
If there everything be okay, we should start with the league, ie. challenges within 3-4 days 
Please, slowly start to animate your members...
We can already start our 1st challenge, for Athens it will be vs Portland with starting day March 1st. Our 2nd challenge for Athens will be vs Beograd on March 23 with starting day April 1st.
Good luck to all 

Yes .. or we will begin with rounds of 20 days.
Nopi put forward a nice idea .. and this yours is somewhere with that idea. They can play the third with a third of all groups ... fourth team with a fourth from all groups .... and the fifth with the fifth from all groups, and we shall determine the schedule ... or can those teams who have not passed in the knockout stage randomly divided into new groups of 3 teams and these won points, with points are awarded already in groups, to decide who goes to the first division, and who in the second.