DNA confusion

[brigidmac]

 are they related to both ancestors along the lines tho In some cases like that  they may be descended from half siblings or there may be an informal family adoption where a daughter takes in mother's child so DNA distance is smaller than you'd expect
My grandfather was a product of a remarriage  so I match ALL descendants of his half sibling who have tested and his full brothers daughter but the half siblings descendants from both mother and father have lower matches to myself and my cousin