What can we do if we accidentally buy tamarind puree instead of paste? My wife was planning to make us pad thai, but accidentally bought tamarind puree instead of tamarind paste.  

We would like to still use the puree if possible - is there any way we could use the puree instead?  Is the difference noticeable enough that our recipe can't be made with the puree?
The only difference between the two is that puree has a little more liquid.

You should add more puree than the recipe calls for paste to compensate for it being more dilute. 

In some recipes, the extra liquid could be a problem, however, I don't think it will make any difference in pad thai in the quantities that it is used.