You share your father's determination, it seems. And in this case, you are correct. There may well be another way. Vault 87 is located very close to the site of Lamplight Caverns. It is entirely probable that the Vault may be entered from within the caves.
Scribe Rothchild was a member of Elder Lyons's exploration party when it discovered the Pentagon ruins. Rothchild fully believes in the Brotherhood of Steel and its ideals, but he is not a soldier. He's a scientist, and a good one. He is the Senior Scribe of the Citadel and takes his position very seriously. He is also thrilled that the months of bringing Liberty Prime online is yielding dividends.
Rothchild mentions a small detachment of Brotherhood in Chicago, saying that they have fallen off the radar and gone rogue. The only known Brotherhood in and around Chicago is the Midwestern Brotherhood of Steel.
He might taunt the Lone Wanderer in repairing his/her gear, as asking him will yield the answer, "Could I? Yes. Will I? No. Ask Bowditch."
Occasionally, he may initiate a conversation with Elder Lyons by saying "What is it Owyn?" which is unusual as Brotherhood of Steel Member Members and Military Personnel in general normally call themselves by their rank and/ or respective title and last name.
"I'm here for two reasons. One, Lyons needs me. He always has, just as much as I need him. We've been through a lot together, he and I. Two... Take a look around you. Access to this kind of technology, and the benefits it could provide to the Brotherhood, is immeasurable."
"He's in charge of this detachment, yes. He's not in charge of the Brotherhood. As loyal as I am to the man, I can't overlook the fact that he disobeyed orders, and it cost us. The West Coast cut us off completely, once they saw what was going on. So now we're on our own. No communications, no reinforcements. We can't even beat the Super Mutants, and now we're expected to defend against the Enclave? Alone? The situation is... less than ideal."
"It wasn't why we were sent here. Good or bad has nothing to do with it. Lyons knew that, but ignored it. He decided it was more important to save the people here than to obey orders from his superiors. For years he'd try and persuade them to send reinforcements and supplies, all the while stringing them along, saying he was sticking to the mission. Finally, things came to a head. Lyons directly refused orders, and so the West Coast cut us off. No communications, no reinforcements."
"Yes, yes please. Your help would be most welcome. As you know, my main task is the reconstruction of Liberty Prime. A daunting task indeed, given his current state. To get him back on his feet will take not only a good deal of scavenged parts, but I need some special items for his complex systems. In your travels, be on the lookout for sensor modules. That will help me with restoring his electrical components. But what I need most are old cameras. Prime's optics were completely destroyed in the explosion and I can use the components inside to replace them."
"You share your father's determination, it seems. And in this case, you are correct. There may well be another way. Vault 87 is located very close to the site of Lamplight Caverns. It is entirely probable that the Vault may be entered from within the caves."