[Avodah] Inviting Someone On Shabbos Who Uses the Eruv

[M Cohen]

YL asks - We have several Eruvim here in Flatbush. I do not rely on any of
them.
Question: May I invite a couple whom I know will wheel their baby in 
a stroller to eat at my house on Shabbos?  They, of course, do rely 
on the Flatbush eruv [at least one of them].

Ie 
can I give a food item with a hechsher that I don't use, to some who does?
Can I allow my wife carry in an eruv that I don't rely on?
Can I give an item of clothing that my community doesn't wear, to someone
who wears such items?

The answer is the same to all for these types of questions:
If you hold it is asur midinah, then you can't be machshil another in this
isur.
If you hold it to be a chumrah, then another doesn't have to hold of your
chumros.

Mordechai Cohen