“Who or where leave that to”

Question

I was writing an email where I needed to return an item to a person who was not in the office the following day. So I came up with the following and I wonder if it's the the correct way of getting your point across or is grammatical at all?

As I have one of your books and you are not in the office tomorrow, I was wondering where or who to leave that to/with.

Answer 1

English doesn't have any "grammatically valid" construction for this particular conjunction.

Nor would it be particularly useful if there was such a construction. Partly because it would rarely be appropriate, but mainly because OP wondered where to leave that or who to leave that with. The only connection between those two possibilities are the repeated words leave, to and that (which should be "it" anyway). It simply isn't worth trying to fit both possibilities into a single construction to save a couple of words.

Also note that OP's suggestion already uses "or" to conjoin the first two variants (where, who), but a slash to conjoin to, with. At best this would be inconsistent use of "pseudo-syntax" — but in this case it makes no sense, since you can't select "to" from the second pair to create a valid expression.

In such circumstances, normal practice would be to either completely rephrase and state both possibilities fully and grammatically...

I was wondering where to leave it, or who to leave it with. ^[1]

...or (more common in speech) to simply enforce grammaticality for the second possibility only...

I was wondering where or who to leave it with.

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^[1] Per comments below, "who to leave it to" is grammatically valid, but inappropriate in this case, since to "leave [something] to [someone]" means to transfer ownership - normally in the context of a will or bequest, to be actioned after one's death.

Answer 2

Is such detail necessary? Why not simply

I have one of your books, but you are not in the office tomorrow, so how can I return it to you?

The trick is that you are asking for either a person to leave it with or a place to leave it at, so either you need to make each option explicit for clarity, along the lines of

As I have one of your books and you are not in the office tomorrow, I was wondering where or with whom I should leave it.

or reword to avoid the prepositional vagaries of leave, e.g.

As I have one of your books and you are not in the office tomorrow, is there a person or place I can entrust it to?

Answer 3

You can use with. There is no confusion about mistaking the with as belonging to both where and who(m) -- it will be correctly understood as attaching to the latter-mentioned.