Bulk editing table items with modals

I have an application with tables, which contain large data sets - there are many tables, with different amounts of data and different headings and data sets - the data can be edited in bulk by selecting the checkbox next to the items, and then using a corresponding edit button.

In the application there is a standard 'advanced' lookup, that presents as a modal, when there is a large data set (sometimes 10,000+ items), so when editing the 'Owners' for example, I can fire the modal above the table, like so:

However, for some fields, you have to enter some other details as the changes are logged. In one example I have, a change in location needs a reason and a date (This is a hard requirement, I cannot change the fact there must be these checks). So, following the editing pattern I have for the table, I would fire a modal above the content for the items being changed:

But, from this screen, I also need to 'lookup' large data sets.

My problem now is, I need to show a modal from the modal - would the best thing to do here be to slide in the second modal content from the right - pushing the first modal content off to the left when 'lookup' is pressed, and showing a back button? Like so:

Is there anything 'wrong' with this approach? or can any one suggest a better approach?