You mentioned that your timeline is 10 years renting before helping the children. The eldest is 22. If the investment is to provide accommodation, I would expect the eldest to need it in less than 10 years. If it is to provide money for a deposit, perhaps too. But most of all, a property is not a great liquidity.
The 2k rent you mentioned is very low and would make a low return for risk and work involved in such an investment. And with the rpz, you have very little prospect for rent increase. My children are younger, we live in Dublin and have a rental locally. I am currently keeping the rental property because I would expect my eldest to need accommodation in the next 4 years and perhaps before as we have a smallish standard house and personally I don't want to live with adult children. However I don't think it's a brilliant financial idea and find it harder and harder to justify it to myself in a rpz world.