Splicing a Y in 12 strand?

[Gashmore]

What sort of splice would be best to splice a length of 9mm Dyneema 12 strand into the standing part of some 12mm? The primary load will be on the 12mm and the 9mm serves as a position control. I am thinking maybe a double Brummel but the load may vary between the legs and I am not sure how the splice will react if one side goes slack.