  Streamer-blowout coronal mass ejections (SBO-CMEs) are the dominant CME
population during solar minimum. Although they are typically slow and lack
clear low-coronal signatures, they can cause geomagnetic storms. With the aid
of extrapolated coronal fields and remote observations of the off-limb low
corona, we study the initiation of an SBO-CME preceded by consecutive CME
eruptions consistent with a multi-stage sympathetic breakout scenario. From
inner-heliospheric Parker Solar Probe (PSP) observations, it is evident that
the SBO-CME is interacting with the heliospheric magnetic field and plasma
sheet structures draped about the CME flux rope. We estimate that $18 \, \pm \,
11\%$ of the CME's azimuthal magnetic flux has been eroded through magnetic
reconnection and that this erosion began after a heliospheric distance of
${\sim}0.35$ AU from the Sun was reached. This observational study has
important implications for understanding the initiation of SBO-CMEs and their
interaction with the heliospheric surroundings.

Solar and Stellar Astrophysics;Space Physics