About a new European Conservative group, based on numbers from Wikipedia:
Belgium: 1 from Dedecker (Oth)
Czech: 9 ODS (Oth)
Denmark: 2 DFP (UEN)
Italy: 9 Lega (UEN)
Latvia: 1 TB/LNNK (UEN)
Lithuania: 2 Order and Justice (ID)
Netherlands: 2 CU/SGP (ID) and 4 PVV (Oth)
Poland: 15 PiS (UEN)
UK: 25 Conservatives and 1 UUP (Oth)
71 MEPs
Both ways, both UEN and ID are below the threshold for a group. All UEN members will probably go into the Conservative group. ID is now 13 UKIP (probably NI with the assorted fascists), 2 LAOS (not sure, maybe NI), 2 CU/SGP (see above) and de Villiers (probably NI, maybe the new Conservative group).
A far-right group (FPÖ, VB, Attack, FN, Jobbik, PRM, SNS, BNP) has only 18 MEPs. With PVV, 22. Still not enough.
UPyD's MEP will NOT join ALDE and sit with Basque and Catalan nationalists. Pirates probably NI, Lithuanian Poles maybe G-EFA (like PCTVL in Latvia), same for the Latvian Harmony Centre.
Before the elections, PVV announced that they would not be part of any group in the EP. I see no reason why they would join the Conservatives group.
Joining a far right group would be the stupidest thing PVV could do. The Dutch media would have a field day. Geert Wilders is very careful about selecting his candidates, to make sure that no neo-Nazi is standing for the PVV. No way he is joining a group with Jobbik, Attack and the BNP in it.
Maybe Harmony Centre and UPyD will join PES?
There is an independent MEP from Estonia elected. Any idea which group he will join?
UPyD will probably not join PES. They won't be in the same group than PSOE. Harmony Centre, maybe.
The independant MEP is the son of a PES MEP from 2004 to 2009, but he was an advisor for the PM Mart Laar, who was for ''Union of Pro Patria and Res Publica'', a member of EPP. He is near the two parties, according to my research.