Is a Waqf (endowment) valid if it is sound at both ends but interrupted in the middle, such as being designated for one's children, then one's slaves, then the poor?

Primary text

Two opinions exist regarding the validity of such an endowment, similar to one that is interrupted at the termination point. If the endowment is deemed valid, then concerning that portion which cannot be restricted by the condition of extinction (i.e., perpetually enduring), it is nullified. If the extinction of the recipient class can be considered, there are two opinions on whether this consideration is upheld or nullified, similar to the issue of interrupted termination.