dividends declared but not paid at death of life tenant

[Brightonian]

The life tenant died on 8 April, at which time there were several dividends that were xd. There was also a unit trust income distribution declared but not paid. The trust funds now go into an existing discretionary trust for the settlor's grandchildren.
I am preparing the IHT400 etc. I am assuming that the dividends and interest declared but not paid are included in the valuation on IHT418 but nowhere else on the IHT400. IHT100 will also have to be completed.
I am not sure about the income tax side. I think that they should be included on a trust return for the period to 8 April - even though they were not paid. And that they will form part of the estate income, with tax credit from the R185.
However, I am finding it very hard to get my head around this, as there seems to be an argument for leaving it off the SA900 and instead just including it as income of the estate.
It has also been suggested to me that it is the deceased's income, on the grounds that she was entitled to it at death.
There seems very little guidance on this topic.
Can anyone help please?

[maths]

Accrued income of a life interest is included in the life tenant's death estate for IHT (eg dividends due on ex-div shares held in. trust and interest declared but not paid on unit trusts).

For income tax purposes only income received by the trustees before the life tenant's death is treated as the life tenant's.

[Brightonian]

Thank you, Maths. That is very clear and much appreciated.