Annullment of Marriage or Emancipation of Married Slave Girl After Husband Bought Her?

If a free man who married a **slave girl (someone else's]** buys her will she is becomes automatically free or is it the choice of her husband to annul the marriage and keep her as concubine? Confused while reading a section related to chapter on tricks to evade Istibara **"إعلام الموقعين عن رب العالمين "** because Imam didn't mention whether she is free after husband buy her Here is the text > "[فَصْلٌ إبْطَالُ حِيلَةٍ لِإِسْقَاطِ الِاسْتِبْرَاءِ] فَصْلٌ > [إبْطَالُ حِيلَةٍ لِإِسْقَاطِ الِاسْتِبْرَاءِ] وَمِنْ الْحِيَلِ > الْمُحَرَّمَةِ الْبَاطِلَةِ أَنْ يَشْتَرِيَ جَارِيَةً وَيُرِيدَ > وَطْأَهَا بِمِلْكِ الْيَمِينِ فِي الْحَالِ مِنْ غَيْرِ اسْتِبْرَاءٍ > فَلَهُ عِدَّةُ حِيَلٍ، مِنْهَا: أَنْ يُزَوِّجَهُ إيَّاهَا الْبَائِعُ > قَبْلَ أَنْ يَبِيعَهَا مِنْهُ، فَتَصِيرُ زَوْجَتَهُ، ثُمَّ يَبِيعُهُ > إيَّاهَا فَيَنْفَسِخُ النِّكَاحُ، وَلَا يَجِبُ عَلَيْهِ اسْتِبْرَاءٌ؛ > لِأَنَّهُ مِلْكُ زَوْجَتِهِ، وَقَدْ كَانَ وَطْؤُهَا حَلَالًا لَهُ > بِعَقْدِ النِّكَاحِ؛ فَصَارَ حَلَالًا بِمِلْكِ الْيَمِينِ." Source: https://app.turath.io/book/11496?page=847