I feel like at the absolute outside, LW could bring a container but leave it in the car, so that if leftovers are offered they could claim to have the thing and offer to go get it rather than do the tupperware dance in the machetunim's* kitchen. But I don't know how plausible such a claim would even be.
* For the unfamiliar: machetunim, a Yiddish mass noun meaning "child's parents-in-law." (Your child's father-in-law is your machuten; your child's mother-in-law is your macheteynista. The ch is in each case guttural, kh, not the consonant at the beginning and end of "church".) I was going to say that however among people who are likely to use the word "machetunim" this sort of problem would be unlikely to come up, but then I remembered that I am the product of a mixed marriage myself (half Jewish/half Puritan, guilt and shame), so never mind.
no subject
* For the unfamiliar: machetunim, a Yiddish mass noun meaning "child's parents-in-law." (Your child's father-in-law is your machuten; your child's mother-in-law is your macheteynista. The ch is in each case guttural, kh, not the consonant at the beginning and end of "church".) I was going to say that however among people who are likely to use the word "machetunim" this sort of problem would be unlikely to come up, but then I remembered that I am the product of a mixed marriage myself (half Jewish/half Puritan, guilt and shame), so never mind.