Not sure if this is still accurate ( if any have died/moved on):
Simba, Nala, Enzi and Nyota were born to Malaika in 2011. They were the second litter born in 2011 (the last litter before them was born in 2007). When they were old enough they joined the pride in the second lion reserve led by Nibalo (arrived in 2010) which consisted of 12 lions already.
Yendi and Nibalo produced a litter of 4 cubs in March 2011 (3 females: Tanya, Kianya, Eve and 1 male: Klaus). Nibalo also mated with Luna in 2011 and produced 2 cubs: Sylvester (M) and Kink (F). (Luna mated with Hugo in 2013 and produced four cubs: Sola, Zahra, Alika, and Ebele, all six were moved to Folly Farm in 2014).
So, at a guess:
Pride 'B'
* Nibalo (assuming he is still living, I have not seen any posts suggesting otherwise).
* Yendi (again, no evidence of death)
* Malaika (no evidence of death)
* Simba, Nala, Enzi, Nyota (possibly moved around to prevent inbreeding)
* Tanya, Kianya, Eve and Klaus (again possibly moved)
* Sylvester and Kink (possibly moved)
That makes 13 although I am unsure of the fates of Jasira, Mildred, Sweet Pea and Little Jas so potentially 17.
As for Pride 'A', that is trickier. After the unfortunate events of 2014:
Longleat announced that the five aggressive lions (Louisa and her four cubs) were potentially putting the other 21 lions at risk so they were PTS. Henry was also PTS as a result of an attack by said animals. Longleat announced it would send off five lions from the same enclosure to other zoos (these would have been Hugo, Lunya?, Nikita, Kimya and an Unknown? fifth lion)
Pride 'A' (nonexistant)
* Henry (PTS)
* Hugo (now at Folly Farm)
* Louisa (PTS along with four cubs (I do not know if they were ever named)
* Lunya (not sure if this is the same animal as Luna (now at Folly Farm or another individual)
* Nikita (Now at Dartmoor)
* Kimya (Now at Dartmoor)
To my knowledge Longleat has had no births since 2014? (Please correct me if I am wrong)