Schedule E - Where to put shared expenses?

[Daniel Smith]

Where do you put your "shared" expenses on a Schedule E? I have four rental properties, and there are some costs shared between them. For instance, an umbrella insurance policy, supplies, PO box rental expenses, travel expenses, home office expenses.

What's the best practice here? Divide the costs up by four and allocate a portion to each property? Or just make "Property A" the grabbag place for all of these indirect expenses?