Trust deed power

I am dealing with a lifetime trust in which it states:

“During the lifetime of the Settlors the power to appoint new trustees shall be vested in the Settlors.”

There are four settlors. Two are able to act. One has died and the other has lost capacity. My initial view was that the two settlors who are able to act can use this power. However, I am starting to have doubts about whether this is possible given that one settlor is still alive but has lost capacity. Would it be possible for those settlors able to act to use this power or does the loss of capacity of one settlor who is still alive prevent the power from being used by the others?

Many thanks

James

If there is no express provision to remove the incapable trustee, then s36(1)(b) TA 1925 may assist the remaining trustees, or beneficiaries could act under s19 ToLATA.