Does guardianship matter to securing a final resting place for my parents?

There's an insane amount of arguing about guardianship regarding my parents who are both ill, etc.....my question is regarding securing a final resting place for them, 3 siblings did the legwork & want to come together and hold a spot, initial cost would be split among the 6 siblings, some of the other 3 were in agreement but another one is saying that guardianship has to be established first, i know that's not the case, the reality is that this person wants to control & have the final say on every little issue, even this.....meanwhile it's not as if anyone else has contributed with any additional ideas, suggestions.....here's the main question: should the 3 that are in clear agreement move forward and put money to hold this spot? whoever the guardian ends up being (sibling or court appointed 3rd party), can they turn around & decide against this decision, and basically say, too bad that the 3 wasted their money, the family member would be capable of that but what about the 3rd party?? wouldn't pre-planning be seen as the responsible thing to do??