1. Islamic law recognizes two types of heirs, the first being Sharers, and the second being Residuaries. A relative who is a Sharer will take a specified portion of the deceased's estate irrespective of anything else excepting for one important exception being the Rule of Awl and Radd. A relative who is a Residuary will take whatever is left over, once the Sharers have taken their specified shares.
2. The share taken by each sharer will fluctuate in certain circumstances. A sole daughter takes a half share. Where the deceased has left behind more than one daughter, all daughters jointly take two-thirds. However, these two rules apply only in cases where the deceased has left behind no sons. If the deceased had left behind son(s) and daughter(s), then, the daughters cease to be sharers and become residuaries instead, with the residue being so distributed as to ensure that each son gets double of what each daughter gets. Lineal descendants (such as sons) exclude brothers and sisters, and therefore, the share of brothers and sisters (whether full, consanguine or uterine) will become nil in the presence of such descendants.