Subject to section 5 of this Act, where brothers and sisters of an intestate or of an ancestor of an intestate (in this section referred to as “collaterals”) have right to the whole, or, in a case to which subsection (1)(b) of the last foregoing section applies, to a half, of the intestate estate, the collaterals of the whole blood shall be entitled to succeed thereto in preference to the collaterals of the half blood; but where the collaterals of the half blood have right as aforesaid they shall rank without distinction as between those related to the intestate, or, as the case may be, the ancestor, through their father and those so related through their mother.