How to prevent a resistor receiving a too high power?
Yes, you can use multiple resistors in various combinations of parallel and series to get higher dissipation.  However, consider the heat coupling between the multiple resistors.  If a significant portion of the heat from one resistor gets to another, the total dissipation of that resistor will have be less to stay in spec.

Do the math.  10 volts accross a 50 &Omega; resistor causes 2 watts of dissipation.  How can you possibly expect a resistor to adhere to any of its specs when you violated its maximum dissipation, in this case by a factor of 8 no less!?

As soon as you violate any spec in the datasheet, the manufacturer no longer promises any of the other specs will be adhered to.  If you violate a absolute maximum spec, the part can be irreversibly damaged.  It can fail other specs later in subtle ways, or it can catch fire or vanish into a greasy black mushroom clould without notice.