Criminal Law Questions? Ask a Criminal Lawyer.
Law enforcement (either police or child services) could decide that there is probable cause to arrest you and remove the children from your custody, or they may do nothing, because they didn't find anything.
In order to force you to submit to a swab test, you must be arrested for something. And, it may be the case that in order to be arrested, the government needs a swab test.
Which would mean that the government can't touch you or your kids.
Hope this helps.
Terms and Conditions: By your continuing in this conversation with me, or by your clicking “Accept”, you are expressly agreeing to all of the following: (1) our communication is for entertainment purposes only; (2) you are not consulting me in my professional capacity as an attorney; (3) you do not seek to establish an attorney-client relationship with me, nor do I with you; (4) you will not rely on anything I say and you will obtain appropriate legal counsel via a traditional/office consultation with an attorney licensed to practice in the jurisdiction where your legal issue arises (and you may not use our communication to avoid taxpayer penalties imposed by the U.S. Dept. of Treasury); (5) by communicating with me in this public forum you are irrevocably waiving any right to privacy, confidentiality and attorney-client privilege concerning the matters discussed. You further separately declare that any payment made by you is not consideration for this contract, nor offered for any services rendered by me on your behalf, but rather is made in genuine admiration and respect for my desire to help others. If you do not agree with these terms and conditions, then you must advise me immediately.
In order to require the swab, you must be arrested and read your rights. And, in order to arrest you, the government needs probable cause, which means better than average proof that you're using meth. Based on your facts, no such proof exists, because if it did, then you would have been arrested already.