Bought Some Liens with a Prior Lienholder... and I Have Questions

[John-Michael Esposito]

BACKGROUND: Today I bought three liens at auction, all of which are for vacant land owned by the same owner. (For reference, the land is located in southern New Jersey.) On all three, there is an investment company who owns a prior tax lien. The prior tax liens were purchased by them in March 2018 for the year 2017 taxes. It appears they made the payments on for all the 2018 taxes, but neglected to pay 2019 and the current 2020 taxes (which I just purchased). 

New Jersey allows you to foreclose after 2 years of non-payment from the owner. I know that the prior lienholder has precedent here, so if they decide to foreclose, I get paid back first. I also know that I can't foreclose as long as their lien is still enforceable, which I believe is 5 years from the date of purchase, after which I think they lose their right to foreclose. (Please correct me here if I'm wrong, I'm new to this.)

THE QUESTIONS: 

1. Is there anyway to acquire this lien from the previous lienholder, or do I have to wait the 5 years for their interest in the property to expire before I can foreclose? (If not, I obviously don't want to alert them.)
2. If I can acquire it (or even if not, it's fun to do hypotheticals), since they bought it two years ago, would I be able begin the foreclosure process today, or would I have to wait two years from the purchase of my certificate to begin?

And I'll also take your referrals for Tax Lien Attorneys in NJ. Haha.