The two Pirates youngsters, Ngubo and Mkhize have attracted interest from National First Division (NFD) clubs as well as Premier Soccer League (PSL) sides.
Bidvest Wits defender Tebogo Moerane joined the Braamfontein-based outfit in February, from Pirates via Shining Stars where he had spent two seasons on loan from Bucs.
However, according to a well placed source at Bucs, the two youth internationals are likely to stay with the North West-based outfit, Shining Stars.
"Siyanda and khumbulani are playing regularly at Shining Stars, and that's why they are also key members in the junior national teams," the source told Goal.
Seventeen year-old striker Ngubo impressed last December during the 2013 Cosafa under-20 tournament in Lesotho, where he finished as one of the top scorers as SA walked away with the gold medals.
"The management is aware of interest from PSL and NFD teams, but they are both likely to stay at Stars for at least one season. They are developing well there," the source said to Goal.
Centre-back Mkhize, who is 18-years-old, was also part of the Amajita team that lifted last year's Cosafa youth tournament in the Kingdom of Lesotho.
"Unlike in Moerane's situation, his representatives had begged the club to release him, and the management eventually agreed and he got his clearance," the source concluded to Goal.
Mkhize and Ngubo were both part of the SA under-20 squad that drew 1-1 against Cameroon, in a 2015 African U/20 Championship qualifier, first leg clash in Yaounde, on Saturday afternoon.
Amajita's ever-green forward Ngubo scored the team's vital away goal, and the second leg is scheduled to be played in Polokwane in two weeks time.
Nonetheless, it remains to be seen if Pirates will be able to keep hold of the two highly-rated Bucs academy graduates, after releasing their former academy player Moerane early this year.