English to Spanish Law/Patents Law (general) Law / Wills

It sounds to me like it could be "por descendencia" but I'd rather check with the collegues. Here's the text (Will): "Upon the death of my wife, or upon my death if she predeceaases me, my Trustees shall divide the trust property into as many equal shares as there are children of mine then libing, and children of mine then deceased survived by issue. Except as hereinafter provided, my Trustees shall pay over and distribute the shares, so set aside for my then living children, or the children of mine then deceased survived by issue, outright free of the trust" THANKS IN ADVANCE!!!!!