Is it permissible to bring in a partner (the questioner's brother-in-law) into a rented shop, on the condition that the partner pays half or slightly more than half of the shop's value, and they divide the monthly rent, knowing that the amount paid to the questioner can be disposed of as he wishes, and that this partnership is temporary?

It is permissible to rent half of the shop and then lease it to another person, or to keep it rented to the first tenant and share the rent. This is permissible. Sheikh Khalil Al-Maliki said: "And renting out what has been rented." And Sheikh Al-Islam Ibn Taymiyyah said: "It is permissible for the tenant to rent out the leased property to someone who takes their place for the same rent or more." For the second contract to be valid, it must take effect after the period for which the first tenant rented the property has ended, bearing in mind that either party may terminate a monthly rental agreement whenever they wish. You may dispose of the amount paid to you as you please, and the subscription period must be specified at the time of contracting. However, if you will return the amount after the company ends, this is a loan that brings benefit, which is usury (riba).