Creating a modern, hyphenated, or combined surname blending both parents’ family names is permissible in Islam, as long as it does not obscure or falsify the child’s true paternal lineage — which remains the core underlying principle from the Quranic instruction in Surah al-Ahzab (33:5). Since this practice is a matter of naming convention and modern family preference rather than a religious ritual, couples have flexibility here. The key consideration is ensuring the father’s identity and lineage remain clear and documented (whether through the surname itself, official birth records, or both), so that the child’s connection to their biological father is never in question, regardless of the surname format chosen.