I would like to see relationships within the families denoted in IPUMS-CPS by FTYPE, ie. the equivalent of RELATE but for families not households. In raw CPS this variable is called PRFAMREL. I cannot seem to find the equivalent in IPUMS.
There is currently no IPUMS variable that directly corresponds to the CPS variable PRFAMREL. However, as long as you have not used the select cases option, it is possible to merge the raw CPS data files from NBER onto an IPUMS-CPS data extract. Because the NBER and IPUMS-CPS files share a common sort order, you can sequentially merge (first record to first record, second record to second record, etc.) the data files. I recommend comparing values of sex, age and race for individuals before and after merging to ensure the merge worked correctly.
Hope this helps.