Players can choose to help each based on if the GM allows. The GM picks what sort of help mechanic best suits the situation.
Sum of All
Sum of All is defined by combining all the skill checkd into one. This is defined by where it is impossible or nearly impossible for working together to be deterimental. Example of this is being a combined strebgth push to open a door.
Helping Hand
Helping hand is defined as a single character being tasked as the main roller. Other characters can assist him.
The main character rolls a skill check as usual.
Each helping character describes how they are going to help. They can use any character ability or spells.
The GM decides whether or not a skill check is required, if so the GM sets a DC.
The DC should be the same as the main character’s DC if they are using the same skill, but the GM can make it higher or lower on other skills based on circumstances.
This provides minor or major aid. It can also provide hinderence. On a skill check, major aid is provided on a Critical success while hinderence is provided on a critical failure
Minor Aid
+1 to the Main Character Skill Check
Major Aid
Advantage to the skill check
Hinderence
Disadvantage to the Skill Check.
Combined Effort
Combined Effort is when the party is all doing the same skill with similar effort. An example of this a stealth check through hostile territory.
When you do so you take the average(round up) of everyone’s skills.