| Dasrak |
Mental Resistance and Steadfast Personality are both untyped bonuses, so yes they stack.
There are very few cases where untyped bonuses do not stack. The most common is if they both add the same ability score. Steadfast Personality would not stack with the Paladin's Divine Grace, for instance, since they both add your Charisma bonus.
| Azothath |
Psychic bloodline
Mental Resistance (Ex): At 3rd level, your mind blocks attempts to assail it. You gain a +2 bonus on saving throws against mind-affecting effects. At 9th level, this bonus increases to +4.
Steadfast Personality feat Add your Charisma modifier instead of your Wisdom bonus on Will saves against mind-affecting effects. If you have a Wisdom penalty, you must apply both your Wisdom penalty and your Charisma modifier.
Iron Will feat on your bonus feat list You get a +2 bonus on all Will saving throws.
all of those are untyped and accumulate or stack.
Comment: a sorcerers Fort & Rflx saves are poor, you might want to pump those a bit.