It was a subsidiary of a major insurance company, they obviously didn't know what they were doing, closed in a few years after losing $150 million.I had no luck calling around bank REO departments, so I concentrated on auctions.

This is literally what you got title insurance for.I doubt the title agent you worked with is a direct subsidiary of the underwriter but that is also irrelevant. 

It'll be interesting to see how investors side step this for example forming multiple LLCs/buying through subsidiaries.

My question is this, should I invest using the original LLC, create a separate LLC, or create a subsidiary of the original LLC?

Hall on the tax issue, there are some concerns I would have if you were to operate them as subsidiary LLCs.

( If it's anything like the states, your plan then has to conform to the laws of each subsidiary that you use. 

Summary of case: Hillman had a parent S-Corp and was charging his subsidiary LLCs a property management fee.

For flippers, many seem to have a parent company that owns subsidiary LLCs.

(I have no affiliation with Eddie Speed, or any subsidiary.)

Parent-subsidiaryA parent-subsidiary controlled group exists when one or more chains of corporations are connected through stock ownership with a common parent corporation; and:80% of the stock of each corporation, (except the common parent) is owned by one or more corporations in the group; and Parent corporation must own 80% of at least one other corporation.2.