HI Alenajdro,
the 'old' ACIG.info forum is still online (since 1999). ;-)
Anyway... yes, they seem to be in the process of doing that. This morning, saw a video shown a column of at least one TR, some 11km long..... almost exclusively MBT.
Re. Ukrainian reserves: AFAIK, only the 92nd was involved in operations north of Kharkiv. 3rd and 4th Tank are still in tehe Siversk area.
Re. RFA's second echelon: they're definitely bringing yet more stuff in. So, yes, this time there appears to be a second echelon.