Your father can very well start another business but to utilise the company's land, your father has to enter into a lease agreement with the company for the purpose of this proposed business on the company's land.
A resolution to be passed by the directors/partners to lease out company property on rental basis.
Your father is just a partner in that company hence he has to obtain the proper permission from the company to start his business on the company's land.
According to Section 14 of the Indian Partnership Act, 1932, depending upon the contract between the partners, the property of the firm includes all the property which was originally brought into the stock of the firm, or acquired through purchase or some other means. It also includes all the rights and interests which are associated with such property. Such property should have been acquired by or for the firm, or for the purposes and in course of the business of the firm.
One of the imperative liabilities upon the partners in a partnership is to use the firm’s property exclusively for conducting partnership business. The partners may agree with variance but such disagreement must be endorsed by a specific agreement to that effect.
According to Section 48(b)(iv), if there is any remaining assets even after applying the said assets in accordance with the provisions in clauses (i), (ii) & (iii) of Section 48(b), then such asset shall be distributed among the partners in the same proportion in which they were entitled to profit sharing.
Therefore you may ask your father to peruse the partnership deed once again fully and properly before taking any decision in haste.