Joint settlor - Gifts to a DT

I would appreciate if someone can assist with the following scenario:

Parents are trying to achieve the following:

B2L property 1 (MV £300K) – owned by H & W as joint tenants – they want to gift their share of this property 1 to a “DT Son” for the potential benefit of their adult son and his children
B2L property 2 (MV £300K) – again owned jointly by H & W as joint tenants – they want to gift their share of this property 2 to a “DT Daughter” for the potential benefit of their adult daughter and her children.

The parent want to give their son and daughter a separate property each so that there is “dis-agreements” between the children at a future date.
The clients would like to have 1 DT for each property (to reduce admin). They are aware and accept the 10 yr anniversary charges and protection issues.
Any suggestions as to how to achieve the client’s objective would be appreciated.

I have informed that eg DT A - if the first DT A has 2 settlors and say H dies - then income tax becomes complex as you have two sets of rules applying to one trust (settlor alive/dead)
I have not come across this and any clarification would be appreciated.)

Chetan Parekh
CHJ