Best way to combine seeds for random number generators to ensure high quality random numbers

I have some seeds generated for each item that's unique for each group. But I want to provide another seed parameter for the UI that allows the user to get different random values.

Right now I am combining the seeds in this manner but I am not sure if there is a better way. I want to generate 3 different seeds that will generate 3 random numbers.

float newSeed = groupSeed + groupSeed * userSeed + 917 * seed * groupSeed - 8872 * groupSeed + userSeed;

Should I simply do this instead?:

float newSeed1 = groupSeed + userSeed + 1887;
float newSeed2 = groupSeed + userSeed + 55537;
float newSeed3 = groupSeed + userSeed + 45634;

I don't know how can I combine these 2 seeds to generate 3 new seeds that differ wildly from each other.