It is permissible to base one's intention for Ihram on the intention of another Sahih Muslim 1221 b
Arabic hadith text
وَحَدَّثَنَاهُ عُبَيْدُ اللَّهِ بْنُ مُعَاذٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا شُعْبَةُ، فِي هَذَا الإِسْنَادِ نَحْوَهُ .
Translation
This hadith has been narrated by Shu'ba with the same chain of transmitters.