Thanks for the clear and concise project description. Although I am new to this site I have long (about 20 years) experience in AutoCAD and AutoLisp and other related things.
I think you require two separate routines. One for moving all the entities in drawings from user selected point to the point 0,0 and another for inserting multiple drawings as blocks in multiple files.
If my guess is correct, you want to move all the entities from drawings from selected point to the point 0,0 so that you want to modify the insertion point of the drawing, when the dwg is inserted in another dwg as a block. I will like to tell you that "INSBASE" is the right system variable for doing so. Sorry if this is not what you want.
First requirement can me met using Autolisp routine and the for the second, it is better to opt for macro or external VB as it will be difficult to type the block name in Autolisp command prompt and in macro, drop down list can be provided.
Thanks and looking forward for your positive reply,
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