Two cross-border law firm unions announced this year have abandoned the typical “merger” arrangement in favor of a Swiss-born structure that creates separate partnerships within the firms, limiting liability but also raising questions of how effectively the firms will be able to integrate their lawyers.

Sonnenschein Nath & Rosenthal on Wednesday said it would combine with London-based Denton Wilde Sapte, just weeks after Hogan & Hartson closed its deal to combine with the U.K.’s Lovells. Both firms have put into place a “Swiss verein,” a structure increasingly used by global accounting and law firms. Verein is German for union.