Praise be to Allah.
Secretions from the vagina are taahir (pure), but there is a difference of scholarly opinion as to whether they invalidate wudoo’. Some of the scholars think that they do invalidate wudoo’, unless they are continual, in which case they come under the rulings on incontinence. In that case, the woman should do wudoo’ after the time for each prayer begins, then she may offer whatever she wishes of obligatory and nafil (supererogatory) prayers with that wudoo’, and emission of those secretions will not matter.
Some of the scholars are of the view that these ongoing secretions do not invalidate wudoo’, because there is no evidence to that effect.
To be on the safe side, one should do wudoo’, but if that is too difficult, then there is nothing wrong with not doing it, because the view that the secretions do not invalidate wudoo’ is a strong view.
Based on that, you can do wudoo’ before or after the adhaan of Maghrib, and keep your wudoo’ until you pray ‘Isha’ at the appropriate time.
But we have explained in the answer to question no. 39494 that if it is too difficult for one who suffers from incontinence – whether in terms of urine, gas or secretions – to do wudoo’ at the time of each prayer, it is permissible for him to join Zuhr and ‘Asr, and Maghrib and ‘Isha’, offering two prayers together with one wudoo’.
And Allah knows best.