st: Identifying subfamilies (2nd+ marriages) within records of families

[Anna Reimondos <areimondos@gmail.com>]

Hi,

I have a dataset of families which looks something like this:

The first variable is a family id, then there is a registration
number, and a variable identifying whether the person is the wife,
husband or child.
In the example below there are two families. In the first family there
is a wife, husband and kids. In the second family the woman has had 2
marriages. In the first she had 2 children, and in the second marriage
she had one child. What I would like to do is create a variable called
'familynum' which will number the different families within the main
family.

NB: There is no registration or familynum for the woman.

     family   reg        person        familynum
	1         		Wife	(1)	
	1	693		Husband(2)	1
	1	693		Child	(3)	        1	
	1	693		Child	(3)	        1
	2			Wife	(1)		
	2	542		Husband(2)	1
	2	542		Child	(3)	        1
	2	542		Child	(3)	        1
	2	879		Husband(2)	2
	2	879		Child	(3)        	2


I have done similar things before, and I know the solution is probably
very obvious...but I am having a blonde moment.

Thanks
Anna
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