On Thu, Mar 26, 2020 at 1:21 PM David Nalesnik <address@hidden
> although it does the job I still wonder if the "tweak" (?) method suggested by Mark can work too, so to have multiple shape commands together, instead of a shapeColumn.
Won't work, hence the elaborate code. From the Notation Reference
"Known issues and warnings
It is not possible to modify shapes of ties or slurs by changing the
control-points property if there are multiple ties or slurs at the
same musical moment – the \tweak command will also not work in this
case. However, the tie-configuration property of TieColumn can be
overridden to set start line and direction as required."
Thank you David, now I have a clear idea about the status of the issue.