You can't draw an extra regular tree unless F is partnered to someone at the outer edge of their siblings. If, by chance, they are, then you can go upwards but beware that the further you go back with both trees, they will clash. If (as here apparently) they are in the middle of that set of siblings, the only way to draw a regular tree, will be to reorder the siblings - which you might dislike for good reason.
One way out of this is to call on the time honoured idea of a connector - for instance, a circle with some sort of code in. (Circles were the standard connector in flow charts, I think). F will have a line going up - not to their parents, but to a connector. Somewhere over to the right (perhaps) you then draw another connector with the same code, that then goes up to F's parents. And from there upwards, you draw a normal tree.
Another possibility is to draw the line from F to their parents but accept that it will cross the line down to D. Flow charts had all sorts of options for crossing lines that are not meant to touch, such as short curves interrupting a straight line but this idea can get messy quickly, especially if F also has siblings on the drawing. Personally, I prefer the clean break of a connector, but you will have to try and experiment.