* Merge needed variables from the HR and IR files onto the KR file
* This illustrative example just adds one HR variable and some v75* variables
*  from the IR file.  You would add other variables. 

* Illustrated with NFHS-5

* Specify workspace
cd e:\DHS\DHS_data\scratch

* Prepare HR file
use "...IAHR7EFL.DTA", clear 
rename hv001 cluster
rename hv002 hh 

* keep the merging variables and other needed HR variables
keep cluster hh hv201
save HRtemp.dta, replace

* Prepare IR file
use "...IAIR7EFL.DTA", clear 
rename v001 cluster
rename v002 hh
rename v003 line
*keep the merging variables and other needed IR variables
keep cluster hh line v75*
save IRtemp.dta, replace

* Prepare KR file
use "...IAKR7EFL.DTA", clear 
rename v001 cluster
rename v002 hh
rename v003 line

* keep just the merging variables
keep cluster hh line
save KRtemp.dta, replace

* Do the merge, starting with KR, then adding IR and HR
use KRtemp.dta, clear

* m:1 because many children to one woman
merge m:1 cluster hh line using IRtemp.dta
tab _merge

* _merge=2 for women in the IR file who do not have a child in the KR file
keep if _merge==3
drop _merge

* m:1 because many children to one household
merge m:1 cluster hh using HRtemp.dta
tab _merge

* _merge=2 for households in the HR file that do not have a child in the KR file
keep if _merge==3
drop _merge