Size of related subfamilies

Hello! Can someone confirm whether or not there is an existing variable for number of people in a subfamily? I’m looking to use this to construct a subfamily poverty level. E.g., to have a poverty level for related family members who are designated as their own subfamily, which does not take into account the incomes of the household head and their immediate family. In other words, I want to calculate poverty for individuals, their spouses, and dependent children, and in order to do so it would be useful to have subfamily size. Any help is much appreciated.

There is not currently such a variable in IPUMS USA. You can easily create this variable using a combination of SAMPLE, SERIAL, and SUBFAM. For example in Stata you could type:

bys sample serial subfam: egen subfam_size = total(1)