If you want a single commit you don't need to rebase your development branch. Just add your commit, and then merge squeezing the branch into a single commit.

Example using git "rebase" in the work branch.md

Prepare the test environment

# Create the git repository
mkdir test2
cd test2
git init

# Add some files
echo "Content" > file1.txt
echo "Content" > file2.txt
git add .
git commit -m "Initial commit"

# Check commits
git log --oneline 

The result:
c14c3f6 (HEAD -> master) Initial commit

Add one more commit

echo "Added a new line" >> file1.txt
git add .
git commit -m "Second commit in master"
git log --oneline 

The result:
1c4db7a (HEAD -> master) Second commit in master
c14c3f6 Initial commit

Create a branch and several commits

git checkout -b branch1
echo "More lines in fileee1" >> file1.txt
git add .
git commit -m "Add more lines on file1"
sed -i -e "s/fileee1/file1/g" file1.txt
git add file1.txt
git commit -m "Fix typo"
echo "*.txt-e" >> .gitignore
git add .
git commit -m "Added .gitignore"
git log --oneline

The result:
14bdb2d (HEAD -> branch1) Added .gitignore
db26032 Fix typo
e7596e0 Add more lines on file1
1c4db7a (master) Second commit in master
c14c3f6 Initial commit

Now, rebase working branch into a single commit

git reset --soft master    # This is the equivalent of "git rebase --interative master" where I select FIX-UP
git add . 
git commit -m "Rebase FIX-UP"
git log --oneline

The result:
e697511 (HEAD -> branch1) Rebase FIX-UP
1c4db7a (master) Second commit in master
c14c3f6 Initial commit

Merge the rebased branch.

git checkout master
git merge --no-edit branch1
git branch -D branch1
git log --oneline

The result:
06f98ca (HEAD -> master) Merge branch 'branch1'
e697511 Rebase FIX-UP
1c4db7a Second commit in master
c14c3f6 Initial commit

Create another branch and squash commit

git checkout -b branch2
echo "Add one line" >> file1.txt
git add .
git commit -m "Add one line to file1"

echo "Add other line line" >> file1.txt
git add .
git commit -m "Add other line to file1"

git log --oneline

The result:
0c83bd3 (HEAD -> branch2) Add other line to file1
321cb1e Add one line to file1
06f98ca (master) Merge branch 'branch1'
e697511 Rebase FIX-UP
1c4db7a Second commit in master
c14c3f6 Initial commit

Now, rebase working branch into a single commit

git reset --soft master    # This is the equivalent of "git rebase --interative master" where I select FIX-UP
git add . 
git commit -m "Rebase branch2 FIX-UP"
git log --oneline

The result:
14665f1 (HEAD -> branch2) Rebase branch2 FIX-UP
06f98ca (master) Merge branch 'branch1'
e697511 Rebase FIX-UP
1c4db7a Second commit in master
c14c3f6 Initial commit

Merge the rebased branch.

git checkout master
git merge --no-edit branch2
git branch -D branch2
git log --oneline

The result:
14665f1 (HEAD -> master) Rebase branch2 FIX-UP
06f98ca Merge branch 'branch1'
e697511 Rebase FIX-UP
1c4db7a Second commit in master
c14c3f6 Initial commit

History log of the file1.txt

git log -p file1.txt | grep commit

Example using git "squash" to merge.md

Prepare the test environment

# Create the git repository
mkdir test1
cd test1
git init

# Add some files
echo "Content" > file1.txt
echo "Content" > file2.txt
git add .
git commit -m "Initial commit"

# Check commits
git log --oneline 

The result:
5852f1b (HEAD -> master) Initial commit

Add one more commit

echo "Added a new line" >> file1.txt
git add .
git commit -m "Second commit in master"
git log --oneline 

The result:
447644d (HEAD -> master) Second commit in master
5852f1b Initial commit

Create a branch and several commits

git checkout -b branch1
echo "More lines in fileee1" >> file1.txt
git add .
git commit -m "Add more lines on file1"
sed -i -e "s/fileee1/file1/g" file1.txt
git add file1.txt
git commit -m "Fix typo"
echo "*.txt-e" >> .gitignore
git add .
git commit -m "Added .gitignore"
git log --oneline

The result:
349c432 (HEAD -> branch1) Added .gitignore
f0c54d2 Fix typo
ba09ab8 Add more lines on file1
447644d (master) Second commit in master
5852f1b Initial commit

Now, merge squashing into a single commit

git checkout master
git merge --squash branch1
git commit -m "Squashed commit"
git branch -D branch1
git log --oneline

The result:
c709e2c (HEAD -> master) Squashed commit
447644d Second commit in master
5852f1b Initial commit

Create another branch and squash commit

git checkout -b branch2
echo "Add one line" >> file1.txt
git add .
git commit -m "Add one line to file1"

echo "Add other line line" >> file1.txt
git add .
git commit -m "Add other line to file1"

git log --oneline

The result:
016032c (HEAD -> branch2) Add other line to file1
369d482 Add one line to file1
22d5122 (master) Squashed commit
97109fd Second commit in master
6c89f18 Initial commit

Now, merge squashing into a single commit

git checkout master
git merge --squash branch2
git commit -m "Squashed second commit"
git branch -D branch2
git log --oneline

The result:
16e0184 (HEAD -> master) Squashed second commit
22d5122 Squashed commit
97109fd Second commit in master
6c89f18 Initial commit

History log of the file1.txt

git log -p file1.txt | grep commit

The result:
commit 16e0184db9e42bc2abda4f68dd2df94ffd62a87b
    Squashed second commit
commit 22d5122b1e266084f2b29f7ddc9642188ee2a053
    Squashed commit
commit 97109fddda784dd2f5d8ff3cd07b7f3723206ea2
    Second commit in master
commit 6c89f18327f853c7e47537826078672b083c9031
    Initial commit