UD from the past

Hello,

In CA in 2008 we purchased a property at a Trustee Sale.

We went to the home but the people would not come to the door ... made a handful of visits so finally served a 3 day notice naming the former owners and the Eviction Attorney took it from there.

We received a judgment for possession (people left just before the sheriff came) and a money judgment and then filed an abstract of judgment.

We just received a letter from the former owner that they are seeking to buy a home and our judgment showed up.

They claim they did not live at the property when we filed the UD and that we should have known as the mailing address for the tax bill and the grant deed when they bought the home was not the same as the physical address as well as they had filed a BK and their address was available there.

They are wanting to file papers to vacate the judgment based on inadequate due diligence with regards to the UD.

My question is ... was the UD attorney (or us) required to search for alternate addresses when doing a UD? Curious what others do when people refuse to come to the door ... who do you 'sue' in the UD? My understanding is that there must be a name and then you can add Does 1-10, but that you cannot 'sue' Doe as defendant.

My idea was to offer a reduced payoff to make their life easier and to save us time and additional attorney fees.

Suggestions/ideas on how to handle the matter would be appreciated.

Thank you,
Lughead

PS - Happy New Year!!!