"Slave" functionality: open the trv valve but don't demand hot water

Hi. I have a towel rad in my bathroom. I like the idea that my towels are kept dry more than I like to control the temperature in my bathroom.

It would be really useful if i could 'slave' my towel trv to the heating for a time block. By slave, what I mean is that the trv will remain open during the slave slot, meaning when there is demand from any other trvs, the hot water will flow through it too. Perhaps you could even set a max temp like you normally would in a time slot, the only thing about a slave slot is that it doesn't initiate boiler demand, it just remains open so it doesn't create unnecessary boiler demand through a day and can close when the room reaches it's target temp.