It had been previously established that Lewis did not leave a will so Ryan and Micki were named his heirs as his closest relatives. Since Ryan's father is shown here alive and Ryan mentions that Micki's mother "cousin Catherine" is still alive, they would have been in line first without a will.
Although a weapons testing/manufacturing facility, the security guard there appears to allow Micki in without even questioning her as to why she's there or even checking her ID.