Associations in genealogies including king but not first of emperors (8)

I believe the answer is:
linkages
'associations' is the definition.
Although both the answer and definition are plural nouns, I cannot see how one could define the other.
'genealogies including king but not first of emperors' is the wordplay.
'genealogies' becomes 'lines' (line is a kind of genealogy).
'including' means one lot of letters goes inside another.
'king' becomes 'K' (chess abbreviation).
'but not first of emperors' becomes 'ag' (I am not sure about this - if you are sure you should believe this answer much more).
'k'+'ag'='kag'
'lines' going around 'kag' is 'LINKAGES'.
'in' is the link.
Can you help me to learn more?
