First off, I imagine you have a top, front, and side blueprint or atleast a top and either front or side.
Are you trying to get them aligned so that the lines match up?

If so, are the drawings the same dimension across the blueprints? If not, there is your problem. If they are correctly lined up, which for a blueprint they should be then your issue may be how you are importing them into maya. You can texture them onto planes, or import as image planes. Depending on the size/scale of the images you may need to do some photoshop work to get them to line up without having to do any modification inside maya.

If you want to use image planes then select your camera view (top, front, side) click on View >>> Image Plane(Very bottom) >>> Import image. locate your file and you are good to go.