Is it permissible to combine more than one intention in a single prayer, such as the intention for الاستخارة (seeking guidance from Allah) and for a Sunnah (recommended) prayer?

There is no objection to combining two acts of worship in a single intention if they are intertwined (such as the ghusl for Jumu'ah and janabah), or if one of them is intended intrinsically (such as tahiyyat al-masjid with an obligatory prayer or a supererogatory prayer). As for two acts of worship that are both intended intrinsically (such as Maghrib prayer with its rawatib — sunnah prayers), it is not permissible to combine them. Accordingly, it is permissible to perform tahiyyat al-masjid with both obligatory and supererogatory prayers, and istikhara with a supererogatory prayer. However, some obligatory prayers and rawatib do not suffice for others.