UNmerge notes inc. cross notation?

Hi Peoples, I have two problems with UNmerging notes from different voices. Examples are attached.

1st line - bar#3 (bass clef) shows the "merge";- the cross-stave B flat semiquaver masks the dotted minim...
bar#7 shows the effective notation required... but the required cross-stave notation cannot be implemented without masking or overwriting voice.

2nd line shows a similar problem: -
bar#13 (bass clef) 3rd beat shows the problem - voice 1 & 2 share the A natural - BUT the v1 semiquaver overwries the v2 crotchet. Bar#15 shows the score notation as required... but only by virtue of inserting a non-requisite accidental.

I have spent considerable time trying to resolve by using different voices and perusing the on-line manual...

Please can somene help me to resolve these issues, thank you.