Leaving electoral space to an ally is a very tricky situation. The BJP has done that in MH repeatedly and suffered the consequences.
The BJP gave away Jan Sangh bastions of Thane and Ratnagiri to ally Shiv Sena. The result is that Sena has MPs from both these seats n 7 MLAs

Recently the BJP gave away its seat of Dahanu LS to the Sena in LS 2019 in lieu of alliance. It's own MP Rajendra Gavit had to reluctantly join the Sena.
Result is the BJP was wiped out from the Palghar district. It is the same district where BJP had 2 MLAs

BJP had even won the bypoll in Palghar after its MP the Late Chinataman Wanaga passed away.
Palghar LS is on the MH Guj border and has large number of tribal votes. Cong MP Damu Shingda won the seat 7 times. Took a lot of effort by the BJP and RSS to wrest this seat from Cong

And yet it was given away in alliance dharma. Result is BJP got wiped out totally from the district. Much against the run of play as BJP is the leading party in Thane (Palghar was carved out of Thane). BJP got even more seats than the Sena in the entire Thane district

The same challenge is now before Sena, NCP and the Congress. U hear a lot of MVA leaders say that we will fight the municipal poll alone and then ally post poll.
Be it Cong's Satej Bunty Patil of Kolhapur, NCP's scamster Chagan Bhujbal in Nashik or Cong's Bhai Jagtap in Mumbai

No one is ready to give up space in their strongholds. But they are not averse to share seats in their ally's stronghold.
NCP wont like to share Nashik, Pune, PCMC seats with Cong or Sena, but would love seats in Mumbai n Thane from Sena. Similarly for the others