What Relation Is My Daughter-in-law's Sister To Me?

To expand the inquiry a little … (sorry)    While Nick is now my Son-in-Law, having married my daughter, I have been considering the proper relationship term for the rest of Nick’s siblings & relations to myself…..:    At the most general level, we may now be related by marriage but…… only my daughter can claim “in-law” relations to the rest of Nick’s siblings    With no direct lineal or collateral consanguinity….. OK so I had to look them up too…. (i.e. No direct or partial blood-line) our relation is probably nearer to the Kith in “Kith & Kin”…..(Kin being of the same family with blood-ties)    Otherwise, while there is some relationship but definitely not “in-laws” & since the law does not recognise half-measures in these cases & deals with black-white, positive-negative, yes-no, in-out….. Is not the converse, by definition “out-laws”?    So greetings to my new out-laws….… QED. ?????    OK… so it was originally a tongue-in-cheek question.. :o))    … but since this quandary first arose, Nick’s sister has recently given birth to a daughter, so the question arose again.    Evidently the families are “linked” by marriage albeit with no direct relationship-terms applying to related family trees above Nick & his wife.    Please don’t be overly concerned or waste any time as this is only for curiosity rather than for any serious intent. Thanks for all the instantaneous responses/ideas so far.

I would not think you were related.

There is no relationship at all.

There is no relationship to her sister.

Probably no relation

She is simply that, your daughter-in-laws sister!

Start with "my daugher's sister" . . .who would be your daughter.
Next, by extension, you have "my daughter-by-marriage's sister" who would be your daughter-by-marriage. (See how you're simply adding people into yourexpanded family circle in roles that are already defined and quasi-familiar?)

So, now you have fitted yourself into a proper (familial-social) relationship as respects yourself in the context of your daugher's and her husband's united families; and you would be properely within social graces to treat that sister as if she were your daughter.

Now remember, this is to advise you how you may guide your conduct towards that "daughter" without fear of acting out of turn. .. But, there would also be no harm in your seeking her (and her parents) agreement to a fatherly kind of affiliation.

Now, to close off this topic, remeber that "in-law" relationships are social constructs only and not legal; and they persist as long as marriage persists, but dissolve just as marriage dissolves at the time of a divorce (unless a particular affiliation is carried on by mutual agreement, which is rare).

Your question  reminds... How much our US materialistic culture has diminished our ability to be at ease with making place for ourselves and others in married families. Something families still seem to do readily, as if by second nature, in so many other countries. 

I hope I have accurately sensed the underlying motivation behind your question. And that the bigger picture is what you might have been wanting to see.

She would be your daughter in laws sister to you  I'm sure

There is no relation between the sister of your daughter in law and you.