Cambio de valores rítmicos and un mismo grupo irregular

Cómo puedo cambiar el valor rítmico de un grupo irregular? estoy introduciendo un octillo en un compás de 5/8 y la única opción de valor que Musescore me da es un octillo de corcheas. Quisiera que el octillo fuera de semicorcheas para conservar la tradición de escritura del merengue Venezolano dentro del mismo compás de 5/8. entiendo que matemáticamente es lo mismo pero no es así la escritura y por lo tanto la lectura. No sé cómo lograrlo. Alguna idea?

Hi, i'm transcribing a piece in a 5/8 time signature and occasionally a 16th note eightuplet appears that plays through the whole bar (It is EIGHT 16th notes through the whole 5/8 bar). When I try to put it in, Musescore only gives me the option of writing it as an 8th note eightuplet, still eight notes (mathematically the same duration) but only under the value of 8th notes and not 16th notes. So it never gives me the option to choose a 16th note eightuplet for a whole 5/8 bar, unless I write it under a 5/16 time signature. In order to respect the composer's will i'd like to keep that original notation, since it's also a tradition in the genre (Venezuelan Merengue) and besides it also seems mathematically correct. How could I do that without having to switch the time indication to 5/16? Is there a feature I could refer to in order to choose the values of the tuplets within the same 5/8 time signature?
I appreciate any thoughts and any help on this.