Seems a little complicated and intricate for a beginner like me however.

If an investor has bought the tax lien and taken possession of it, this could make things more complicated.

Investing in a property that you will be living in while splitting ownership will complicate the situation come tax time, and may disallow passive activity losses for your daughter.It is definitely possible to structure this deal to potentially work, but will require a lot of consultation to make sure all your i's are dotted and t's are crossed if you happen to be selected for audit depending on how the invested property is used (rental activity (schedule E) vs itemized deductions(schedule A)).

Look for more complicated types of leads, difficult probates, reverse mortgages, IRS liens etc.

This is pretty complicated and in order to get even close to an accurate answer your question, you'll need to provide the filing/recording dates of the mortgage/deed of trust as well as the FTLs.

I would suggest though that the answer is much more complicated than that.

A real estate transaction is complicated enough without having the sellers using their position in the property, to spite their partner!

It seems to me to be completely unsuitable for a Real Estate application,  for many reasons which are too complicated to enumerate here.    

All the investors I know that have cash to take down these properties can talk numbers in their sleep.Foreclosure costs will vary by state as to judicial and non-judicial as well as pre and post redemption periods.In Georgia we have 30 days to foreclose and no post redemption so we are faster,cleaner,and cheaper than many states.Simply don't defend your value to the bank as you will come across desperate.

The costs can be expensive depending on if it is judicial or a non-judicial state.I would also not float a 2% rate as I could never sell the note off if I need to cash out with that return.If you want to get in with 100% finance then usually you will not land a great price.The reason is I the seller could simply reduce my price to sell to an all cash buyer or reduce a little and land someone willing to put 10 to 20% down which would cover my having to foreclose on them etc. and mitigate the risk.If this seller goes for 2% with nothing down they are really desperate.I am not getting that vibe from your post.good luck