Maybe totally useless and/or out of date info but for years I travelled to places requiring a visa and I used to go through passports at a rate of knots. I had the old passport stapled to the back of the latest and never had a problem with the visa being in the old passport. In fact, more than once, the US immigration lot wrote below the current entry stamp "vis in old passport".
I don't know if this may be of use, I certainly hope so. Good luck!