I have setup: - OR -2.5.8

pclass1 = Sales
pclass 2 = Rentals

Then: -

One field called sales_price which I'm using for the price in property sales and is only in pclass1.
Second filed is called rental_price and I'm using this as the monthly rental price and is only in pclass2

I would like to have the search results shown in Ascending price order.
(Currently they use field city as set in the site config Sortby)

But if I choose sales_price as the Sortby rather than city, the the rentals don't show in the results as they don't have this field assigned to them or rental_price then you don't see the sales_price properties in the results.
Hope I have explained that well enough.

Any ideas of how this can be solved?