Praise be to Allah.
Secretions from the vagina are taahir (pure), but there is a difference of scholarly opinion as to whether they invalidate wudu. Some of the scholars think that they do invalidate wudu, unless they are continual, in which case they come under the rulings on incontinence. In that case, the woman should do wudu after the time for each prayer begins, then she may offer whatever she wishes of obligatory and nafil (supererogatory) prayers with that wudu, and emission of those secretions will not matter.
Some of the scholars are of the view that these ongoing secretions do not invalidate wudu, because there is no evidence to that effect.
To be on the safe side, one should do wudu, but if that is too difficult, then there is nothing wrong with not doing it, because the view that the secretions do not invalidate wudu is a strong view.
Based on that, you can do wudu before or after the adhaan of Maghrib, and keep your wudu 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 wudu 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 wudu.
And Allah knows best.
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