Under Scheme of Amalgamation which is a scheme between the Company its Shareholders and "Creditors ( which would include debenture holders as well) " it is quite standard section/clause which states that all the liabilities of any form of debt/charge/encumbrance etc etc which would include debentures would be transferred to the Transferee Company i.e. in this case the unrelated third party. Also the consents of creditors (atleast 90 percent in value) is required as part of the whole scheme approval process or 75 percent of creditors in the meetings when held, under the Companies Act as well.

Also contractually also for sure there where would be clauses under the DTD ( debenture trust deed) that prior approval is required for any restructuring such as merger/amalgamation etc.

The obligations of the original issuer are transferred to the amalgamated entity by operation of law, as per section 232. The scheme of amalgamation must specifically all liabilities, including obligations under debentures, are vested in the amalgamated company. This means that the amalgamated entity becomes responsible for fulfilling all the terms of the debenture, including payment of interest, redemption, and any other obligations outlined in the debenture trust deed or agreement.

For investors, the amalgamation does not automatically impact their rights or the enforceability of the debenture terms. The new entity assumes the legal obligations of the debenture issuer, and investors retain their rights to receive payments and demand performance under the original terms. However, there may be practical implications for investors, as the amalgamation could change the financial health or risk profile of the new entity. If the amalgamated company has a weaker credit standing or operates in a different industry, investors may face increased credit risk, which could affect the issuer's ability to meet payment obligations.

This will depend on the terms of the scheme. Debenture Holders or the Debtor Trustee would have been given notice of the proposed scheme and voted on it. Most schemes should say that all liabilities, such as debentures, will continue with the merged company, but you will have to check.

Debentures are debt liabilities. Unless otherwise specified and agreed in the transaction documents, liabilities of issuer ( after amalgamation with unrelated entity) will become liabilities of such unrelated entity.

You need to check the docs for how this is governed. The scheme of arrangement will also have to deal with this generally.