Complex sentence: Few hard facts are known about this because Crosse destroyed most of their correspondence after her death as part of a legal agreement; however, the relationship was strong enough that she bequeathed him the only heirlooms her father had personally left to her.
Split into simpler sentences: Few hard facts are known about this because Crosse destroyed most of their correspondence after her death as part of a legal agreement. However, the relationship was strong enough that she bequeathed him the only heirlooms her father had personally left to her.