PB, i realize you may not be able to provide further input but i want to run through this option in my mind and see other peoples' thoughts. if this person didn't know what they were doing and only knew her peripherally, how does she conceal what they are doing and why help if you only know some loosely?
-Person A: someone who owes her a favor bc shes done favors for them. these types of favors are likely arranged among ppl on a need to know basis.
-Person B: a friend from the past. someone who knew EG at a different time in her life and for whatever reason, feels a lifelong bond. possibly viewed her as someone who made some bad choices but was a "good person". lets speculate to get this person to agree, rather than on a need to know basis, they have a few questions so she needs to create a fake story. what would she tell them? maybe she knew she could trust this person to get their hands a little dirty so she lets them know its criminal/evidence against her but not child related. if it was a crime that seemed justified/not a big deal, this person could be trusted.
-Person C: she was recently moving. she asked a friend w large car (or JHs friend, or friend of a friend etc) to pick up some boxes/trash from the move and included Lucas' body in the pile items/trash. you certainly dont need to be close to someone to help w that kind of favor/its the kind of thing ppl often help periphery friends with and maybe hope for some free beer or baked goods in return - ive helped a ton of ppl move and vice versa. this person would be none the wiser what they were transporting at the time.
-Person A or B (could even be a combo of these two descriptions in one person): EG goes to them and does the disposing herself but using their property/equipment. For example, EG goes to a friend with a farm to use their machinery/land to dispose of Lucas or asks a homeless friend to burn a large wrapped object. By EG going to them, this allows EG to provide less of an explanation and/or its easier to lie. and while maybe this person was suspicious/thought it was weird, they didnt connect the dots until after Lucas went missing or this person wanted to keep the dots unconnected bc they have their own secrets .