Can one combine the intentions of the Shafa' prayer, Istikhara, and Salat al-Hajah in two rak'ahs?

It is permissible to combine two acts of worship in a single intention if their foundation is based on overlap, such as the ghusl for Friday and for Janabah, or if one of them is not intended for its own sake, like the Tahiyyat al-Masjid (greeting of the mosque) with another prayer. However, combining two acts of worship that are each intended for their own sake is not valid, such as the Dhuhr prayer and its regular Sunnah prayer (ratibah).

Based on this, Salatul-Istikhara (prayer for guidance) and Salatul-Hajah (prayer for need) are not intended for their own sake, so it is permissible to combine them with the two rak'ahs of Shaf' or Fajr.