Transistors in parallel

I want to use several transistors in parallel to control current through a load. This is to distribute the current through the load across the transistors so that individual transistors with a rated collector current less than that going through the load can be combined to control the load.

Two questions:

1. 
   

   Would an arrangement such as in the schematic below work well? (Resistor values only very roughly approximated).

   
   


2. 
   

   How should the resistor values be calculated? I was thinking of using the range of hfe values for the transistor as follows: calculate two collector currents: for the minimum value of VR, the minimum and maximum collector current for the minimum and maximum hfe values.

   
   

Thanks

^{simulate this circuit – Schematic created using CircuitLab}

Edit: Actually I would remove R-limit, and have VR stretch across the rails, with the wiper connected to R1-R3