As far as media exposure goes, Shannon representing the BL Estate is the only part of the Lee families involved. I don't think I've seen or heard of Robert or Phoebe being involved in anyway. That aspect is a little strange given their previous involvements in projects from China.
As for Shannon's role in the production, I personally doubt they had anyone else in mind other than Danny Chan, so whatever casting of Bruce she was involved in it must have been more of a superficial role rather than one of any substance.
I don't think she speaks well enough Chinese to make any judgement on the acting front, which leaves only decisions on the looks department. And who better than Danny Chan in that regard? Profile wise, after Shaolin Soccer and Kung Fu Hustle, there can't have been anyone else.
'Is this TV series more based on the perspective of Bruce's siblings, rather than that of his widow and daughter?'
Based on the perspective of whatever drama they can fit in over 40 episodes.
You're thinking of the definition of biopic because of the title, and not Chinese tv drama series. Big mistake.
