I think you need to see a Criminal Defense Attorney. But, if the warrant is valid, then the search will be valid one. You may need to see an Attorney to question the validity of a warrant.
DISCLAIMER—This answer is for informational purposes only. It doesn't constitute legal advice. This answer doesn't create attorney client relationship.
If a search warrant was issued, an experienced criminal defense attorney may file a motion to suppress the evidence. The issue is whether probable cause to issue the warrant.
Your connection and interest in the subject matter is not revealed, so I can't begin to judge the extent to which you do or might have accurate information about what your speak. The short answer to the initial question is YES. Most search warrants for residences are based upon information from other people with "inside" information about the premises, sometimes on the word of a single CI. Your post makes it appear that the police searched the house on the word of one of the three occupants of the vehicle without the benefit of a search warrant. Unless they also obtained consent to search from the residents then such a search without a warrant would be blatantly unconstitutional. Whoever has had criminal charges filed against them as a result of the incident you describe need to engage the services of a good criminal defense attorney with significant experience in drug defense. Not much else I can say at this point other than to caution you not to post additional details about this matter on the Internet. A private conversation with qualified counsel is the next step and it should be undertaken without delay.
Great question! Search and seizure law is complicated and tricky. We defense attorneys start with the premise that every serach of a dwelling must be done by warrant. This is what the PA and US Constitutions say. However, there are many exceptions and the law is always changing. In your scnenario it comes down to how reliable was the source of the information (the user who was arrested) and how reliable was it that after her information was given, drugs would be found. I don't know all the facts but i think you should get a an attorney there who is good with suppression/search and seizure law to look closely at the facts. From this limited information it sounds like the search could be challenged. Make sure you have an attorney at your prliminary hearing and have the testimony recorded.