Sampling question for telephone survey. Health sciences researcher out of my area of expertise. I have an assistant calling businesses at random, using a publicly available registry, to ask about their automated external defibrillator (AED). We are sampling without replacement. 

My question is, what happens methodologically if we call one of the registered AEDs (selected by random) and the person/informant can give us info on multiple AEDs on the registry that have not been selected as part of our random sample? We're in this position with a large business who has 10+ AEDs, all of which are registered, but our randomization only selected one of the 10+ devices. It seems crazy not to get info on all the devices to me.

Can/should we include these devices that were not randomly selected? I'm having trouble understanding the implications of sampling these and including them in our analysis. Including these other devices seems like snowball sampling instead of just simple randomized sampling.  

Any help would be extremely appreciated. Thank you!!!
This isn't my field, but statistically speaking, you will possibly invalidate your study if you change the parameters mid stream. 

However, you can gather the extraneous data, since it is cheap to do so. But isolate it and use it only as a guide to future work and, perhaps, to give yourself confidence (not statistical confidence) in the outcomes. 

If this is dissertation work, then knowing what you could have done differently is worth exploring and maybe including. But let the experiment you designed be carried out faithfully. Otherwise, at best, you will just confuse yourself with the results.