This is from (my translation of) Sri Ananta Dasa Babaji's commentary on Sri Prema-bhakti-candrika by Narottama Dasa Thakura:
"In the madhura-rasa or ujjvala-rasa of Vraja, there is a complete absorption in the wondrous parakiya-bhava, wherein an endless variety of enjoyment is revealed. In that highest yugala-ujjvala-rasa, meaning in the incomparable sweetness of Sri Sri Radha-Madhava’s union, lies the pinnacle of enjoyment. The sakhis in Sri Radha’s group have been blessed with the good fortune of tasting that unequalled sweetness. And among them, those kinkaris or manjaris who serve with more affection toward their beloved Sri Radha than Sri Krishna experience a taste that is sweeter and more diverse than any others. The reason is that even the sakhis don’t get the privilege of seeing Sri Sri Radha-Madhava’s most confidential pastimes. Only the minnow-like eyes of the manjaris happily swim as they please in that sea of lila-rasa. By getting the good fortune of this sublimely delightful seva, they truly receive the highest blessing of all. Their natures and moods are so attuned to Srimati’s that She considers the manjaris to be identical to Her own body. Therefore, during times of intimacy, Sri Radha-Madhava feel no hesitation or shyness before the manjaris as they perform their personal sevas. Moreover, as a result of their extraordinary oneness of mood with Srimati, the marks left on Sri Radha’s body after lovemaking also appear unchanged upon their bodies! For this reason, as Sri Rupa Manjari and Sri Lavanga Manjari, the leaders of the nitya-siddha manjaris in vraja-lila, and as Sri Rupa and Sri Sanatana in gaura-lila, they have been called yugala-ujjvalamaya-tanu: those within whom an abundance of yugala-ujjvala-rasa is seen."