It would become a lot LESS complex if we as a nation held our politicians accountable for the LACK of enforcement that has been going on for decades.
I agree with you in this respect; it would be unfair and WRONG for any immigration reform act to send back EVERYONE who is here illegally regardless of case. But that can be sorted out through rational efforts for REAL reform and allowing those we have WILLFULLY ignored for decades and opportunity to meet specific requirements and eventually allowing them to become citizens.
The laws regarding immigrants like you sister-in-law should be simplified allowing for an instantaneous process for permitting citizenship within a year or two of marriage and some minimal classes on the Constititution and minimal English Language courses.
The reform legislation should include a simplified green card process that permits instantaneous checks via computer for any employer and/or agency and if there is a violation of any visa, it is handled firmly and expediently. Any Social Security numbers that match an expired visa should be immediately brought to the attention of immigration and those people picked up and deported.
For those who have been in the country and paying their taxes under the noses of our own officials, they should be given a five year process for legal immigration for permanent residency.
There are a few more reforms that can and should be implemented to make immigration with our Southern neighbors effective, efficient, fair and this will improve relations when there is finally a consistent application of our laws.